阅读说明：本技术 一种检查井盖铸造用熔炼、球化孕育工艺 (Smelting and spheroidizing inoculation process for manhole cover casting ) 是由 唐宇 许顺 刘杲 鲜其祥 于 2019-09-29 设计创作，主要内容包括：本发明公开了一种检查井盖铸造用熔炼、球化孕育工艺,包括以下操作步骤：步骤S1、原料制备；步骤S2、制芯；步骤S3、混砂造型；步骤S4、熔炼；步骤S5、球化孕育；步骤S6、浇铸；步骤S7、震动清砂；步骤S8、抛丸打磨,本发明的有益效果是,该检查井盖铸造用熔炼、球化孕育工艺,通过对现有的铸造工艺进行改进,提高熔炼、球化孕育工艺过程中的各项指标,并对球化过程中的各个环节进行定时、定量控制,使得球化后的原料更加均匀,进而使得铸造出的球墨井盖韧性高,耐磨性好。(The invention discloses a smelting and spheroidizing inoculation process for manhole cover casting, which comprises the following operation steps of: step S1, preparing raw materials; step S2, core making; step S3, sand mulling and modeling; step S4, smelting; step S5, spheroidizing inoculation; step S6, casting; step S7, vibrating and cleaning sand; s8, shot blasting and polishing, wherein the smelting and spheroidizing inoculation process for the manhole cover casting has the beneficial effects that the existing casting process is improved, various indexes in the smelting and spheroidizing inoculation process are improved, and each link in the spheroidizing process is controlled in a timing and quantitative mode, so that spheroidized raw materials are more uniform, and the cast nodular manhole cover is high in toughness and good in wear resistance.)

1. A smelting and spheroidizing inoculation process for casting a manhole cover is characterized by comprising the following operation steps of: step S1, preparing raw materials; step S2, core making; step S3, sand mulling and modeling; step S4, smelting; step S5, spheroidizing inoculation; step S6, casting; step S7, vibrating and cleaning sand; step S8, shot blasting and polishing;

step S1: preparing iron materials to be cast according to a certain proportion;

step S2: correctly installing a core making mold on a core making machine, adding precoated sand with the granularity meeting the requirement into a sand hopper, starting the core making machine, starting manual (automatic) operation when the temperature of the mold is heated to 200 ℃, and enabling the precoated sand to enter the mold from the hopper; removing a blank on the sand core after the sand core of the well cover is demoulded;

step S3: putting quartz sand, bentonite and coal powder into a sand mixer according to a certain proportion, and integrally molding the sand-mixed material and the well cover sand core in the step S2 for later use;

step S4: putting the iron material to be cast prepared in the step S1 into a smelting furnace for smelting and tapping;

step S5: spheroidizing inoculation is carried out on the molten iron produced in the step S4, the newly repaired molten iron ladle must be scalded when the standing time exceeds 30min before the first use and the production process, the molten iron amount in the ladle must be more than 2/3 of the ladle capacity during ladle scalding, the nodulizer is placed into a dam of the molten iron ladle according to the required molten iron amount before tapping, ferrosilicon is added on the dam and tamped, scrap iron is added for covering, the scrap iron is dried and cleaned, and the adding amount of the nodulizer is adjusted according to the actual requirement; the adding amount of the ferrosilicon is adjusted according to actual needs, the ladle is lifted into a tapping hole, when the ladle is stable and the position is proper, after the temperature of the molten iron meets the requirement, all the molten iron is quickly poured into the ladle at one time, the error of the molten iron amount is allowed to be 0-310kg, the spheroidization reaction time is 60-90S, a slag conglomeration agent is added into the ladle after the spheroidization reaction is stable, scum is completely stirred, slagging is carried out for 1-3 times per ladle of molten iron, a triangular sample is taken before a casting furnace after slagging is finished, the spheroidization condition is quickly judged, a spectrum sample is taken for each ladle to carry out chemical component analysis, the process of spheroidization inoculation requires that the chemical components of the molten iron are strictly controlled to meet the process requirement, particularly the sulfur content in the molten iron is;

step S6: preheating a pouring ladle, pouring quantitative molten iron, cleaning impurities in a ladle nozzle, preventing the impurities from flowing into a product, keeping the ladle nozzle and a pouring gate at a certain height, controlling the flow of the molten iron to be smaller and gradually increased when pouring is started, and estimating that the flow of the molten iron is reduced until the molten iron in a sprue rises to a specified height when the molten iron pouring casting is quickly filled, wherein the whole process cannot cut off the flow so as to avoid cold shut of the casting;

step S7: after the product is poured, cleaning the molding sand on the surface of the casting by using a high-frequency vibration shakeout machine, and knocking the sticky sand on the surface of the casting by using an iron hammer;

step S8: and the castings continuously enter the closed shot blasting machine along with the transmission equipment to treat the bonded sand on the surfaces of the castings, the castings after shot blasting are automatically accumulated in a transfer hopper, and the castings after shot blasting are lifted to a designated semi-finished product area by using a crane.

2. The smelting and spheroidizing inoculation process for the manhole cover casting according to claim 1, wherein in the step S1, the iron material to be cast comprises 90-100% of scrap steel and 0-10% of return iron.

3. The smelting and spheroidizing inoculation process for the manhole cover casting according to claim 1, wherein in the step S2, the solidification time of the manhole cover sand core is 80S, the sand shooting pressure is generally 0.15-0.4MPa, and the sand shooting time is 3-155S.

4. The smelting and spheroidizing inoculation process for the manhole cover casting according to claim 1, wherein in the step S3, the sand mixing time is more than or equal to 3min, after the new sand, the old sand and the water are wet mixed for 15S, bentonite, coal powder and additives are added and mixed for 120-150S to form green sand; the sand mixing time is not suitable to be too long, otherwise, the sand is heated to reduce the fluidity, and the strength is influenced.

5. The smelting and spheroidizing inoculation process for the manhole cover casting according to claim 4, wherein the green sand has the quality requirements of 150-200 Kpa of wet pressing strength, 90-160 mm/s of air permeability and 32-40% of compaction rate in order to ensure the integrity of the sand mold in the processes of stripping, running, core setting, mold combination and the like.

6. The smelting and spheroidizing inoculation process for the manhole cover casting according to claim 1, wherein in the step S4, a sample is taken for chemical analysis before tapping, and tapping is prepared after the analysis result is obtained.

7. The smelting and spheroidizing inoculation process for the manhole cover casting according to claim 1, wherein in the step S5, the triangular fracture is silvery gray, the structure is thin, the shrinkage cavity in the center is not obvious, and the spheroidizing is proved to be good when the tapping sound is clear and crisp.

8. The smelting, spheroidizing inoculation process for the casting of the manhole cover according to claim 1, wherein in the step S5, the amount of the added iron filings is preferably that the reaction starts in the ladle when the molten iron is discharged to one third, the position of the spheroidizing agent and the ferrosilicon in the ladle can be determined according to the use condition, when the ladle bottom at one side becomes red, the spheroidizing agent and the ferrosilicon can be placed at the other side and stacked alternately, when the temperature of the ladle bottom is high, the spheroidizing agent and the ferrosilicon can not be poured into the ladle too early, and when the ladle is placed before the tapping, and the slag hanging on the ladle is too thick, the ladle needs to be replaced.

9. The smelting and spheroidizing inoculation process for the manhole cover casting according to claim 1, wherein in the step S6, the pouring temperature is 1400-1430 ℃, and in order to prevent inoculation recession, spheroidizing molten iron is poured within less than or equal to 15min after inoculation.

10. The smelting and spheroidizing inoculation process for the manhole cover casting according to claim 1, wherein in the step S8, a grinding wheel is reasonably used in the grinding process to prevent the surface of the casting from being lost.

Technical Field

The invention relates to the technical field of nodular well lid casting, in particular to a smelting and spheroidizing inoculation process for manhole lid casting.

Background

The nodular cast iron well lid generally divide into circular and square, in the road administration aspect of urban area, generally adopts circularly, because the not easy slope of circular well lid, the safety of the good pedestrian of protection that can be better and vehicle. The spherical well lid is made of nodular cast iron, and the nodular cast iron is spheroidized and inoculated to obtain spheroidal graphite, so that the mechanical performance of the cast iron is effectively improved, particularly the plasticity and the toughness are improved, and the strength of the cast iron is higher than that of carbon steel. The ductile iron is a high-strength cast iron material developed in the 20 th century and the fifties, the comprehensive performance of the ductile iron is close to that of steel, and the ductile iron is successfully used for casting parts which are complex in stress and high in requirements on strength, toughness and wear resistance based on the excellent performance of the ductile iron. Nodular cast iron has rapidly evolved to a very widely used cast iron material second only to gray cast iron. The term "steel is replaced by iron" is mainly used for nodular cast iron.

Disclosure of Invention

The invention aims to solve the problems, designs a smelting and spheroidizing inoculation process for the casting of the inspection well lid, and solves the problems that in the prior art, the content of carbon and silicon required by the original molten iron is higher than that of gray cast iron, the content of manganese, phosphorus and sulfur in the nodular cast iron is reduced, the tapping temperature of the molten iron is higher than that of the gray cast iron so as to compensate spheroidizing and the loss of the molten iron temperature during inoculation, spheroidizing is carried out, namely, a nodulizer is added into the molten iron, an inoculant is added for inoculation, higher pouring temperature and larger size of a pouring system are required, a riser and cold iron are reasonably applied, a sequential solidification principle is adopted for heat treatment, and the produced well lid has poor toughness and low wear resistance.

The technical scheme of the invention for realizing the aim is as follows: a smelting and spheroidizing inoculation process for casting a manhole cover comprises the following operation steps: step S1, preparing raw materials; step S2, core making; step S3, sand mulling and modeling; step S4, smelting; step S5, spheroidizing inoculation; step S6, casting; step S7, vibrating and cleaning sand; step S8, shot blasting and polishing;

step S1: preparing iron materials to be cast according to a certain proportion;

step S2: correctly installing a core making mold on a core making machine, adding precoated sand with the granularity meeting the requirement into a sand hopper, starting the core making machine, starting manual (automatic) operation when the temperature of the mold is heated to 200 ℃, and enabling the precoated sand to enter the mold from the hopper; removing a blank on the sand core after the sand core of the well cover is demoulded;

step S3: putting quartz sand, bentonite and coal powder into a sand mixer according to a certain proportion, and integrally molding the sand-mixed material and the well cover sand core in the step S2 for later use;

step S4: putting the iron material to be cast prepared in the step S1 into a smelting furnace for smelting and tapping;

step S5: spheroidizing inoculation is carried out on the molten iron produced in the step S4, the newly repaired molten iron ladle must be scalded when the standing time exceeds 30min before the first use and the production process, the molten iron amount in the ladle must be more than 2/3 of the ladle capacity during ladle scalding, the nodulizer is placed into a dam of the molten iron ladle according to the required molten iron amount before tapping, ferrosilicon is added on the dam and tamped, scrap iron is added for covering, the scrap iron is dried and cleaned, and the adding amount of the nodulizer is adjusted according to the actual requirement; the adding amount of the ferrosilicon is adjusted according to actual needs, the ladle is lifted into a tapping hole, when the ladle is stable and the position is proper, after the temperature of the molten iron meets the requirement, all the molten iron is quickly poured into the ladle at one time, the error of the molten iron amount is allowed to be 0-310kg, the spheroidization reaction time is 60-90S, a slag conglomeration agent is added into the ladle after the spheroidization reaction is stable, scum is completely stirred, slagging is carried out for 1-3 times per ladle of molten iron, a triangular sample is taken before a casting furnace after slagging is finished, the spheroidization condition is quickly judged, a spectrum sample is taken for each ladle to carry out chemical component analysis, the process of spheroidization inoculation requires that the chemical components of the molten iron are strictly controlled to meet the process requirement, particularly the sulfur content in the molten iron is;

step S6: preheating a pouring ladle, pouring quantitative molten iron, cleaning impurities in a ladle nozzle, preventing the impurities from flowing into a product, keeping the ladle nozzle and a pouring gate at a certain height, controlling the flow of the molten iron to be smaller and gradually increased when pouring is started, and estimating that the flow of the molten iron is reduced until the molten iron in a sprue rises to a specified height when the molten iron pouring casting is quickly filled, wherein the whole process cannot cut off the flow so as to avoid cold shut of the casting;

step S7: after the product is poured, cleaning the molding sand on the surface of the casting by using a high-frequency vibration shakeout machine, and knocking the sticky sand on the surface of the casting by using an iron hammer;

step S8: and the castings continuously enter the closed shot blasting machine along with the transmission equipment to treat the bonded sand on the surfaces of the castings, the castings after shot blasting are automatically accumulated in a transfer hopper, and the castings after shot blasting are lifted to a designated semi-finished product area by using a crane.

In the step S1, the iron material to be cast comprises 90-100% of scrap steel and 0-10% of return iron.

In the step S2, the curing time of the well cover sand core is 80S, the sand shooting pressure is generally 0.15-0.4Mpa, and the sand shooting time is 3-155S.

In the step S3, the sand mixing time is more than or equal to 3min, after the new sand, the old sand and the water are wet-mixed for 15S, bentonite, coal powder and additives are added, and the mixture is mixed for 120-150S to form green sand; the sand mixing time is not suitable to be too long, otherwise, the sand is heated to reduce the fluidity, and the strength is influenced.

The green sand quality requirement is to ensure the integrity of the sand mold in the processes of mold stripping, operation, core setting, mold combination and the like, the green press strength requirement is 150-200 Kpa, the air permeability is 90-160 mm/s, and the compaction rate is 32% -40%.

In step S4, a sample must be taken before tapping for chemical analysis, and tapping is prepared after the analysis result is obtained.

In the step S5, the triangular fracture is silver gray, the structure is thin, the center has an unobvious shrinkage cavity, and the spheroidization is proved to be good if the tapping sound is clear and crisp.

In the step S5, the amount of the added scrap iron is preferably that the reaction is started when one third of the molten iron is discharged; the positions of the nodulizer and the ferrosilicon in the foundry ladle can be determined according to the use condition, when the bottom of one side of the foundry ladle glows, the foundry ladle can be placed on the other side of the foundry ladle, the two sides of the foundry ladle are stacked in turn, and when the temperature of the bottom of the foundry ladle is high, the nodulizer and the ferrosilicon cannot be poured into the foundry ladle too early and need to be poured into the foundry ladle before tapping; when the slag sticking of the ladle is too thick, the ladle should be replaced.

In the step S6, the pouring temperature is 1400-1430 ℃, and in order to prevent inoculation recession, the nodulizing molten iron is poured within less than or equal to 15min after inoculation.

In the step S8, a grinding wheel needs to be reasonably used in the grinding process to prevent the surface of the casting from being lost.

The smelting and spheroidizing inoculation process for the manhole cover casting, which is manufactured by the technical scheme of the invention, improves the existing casting process, improves various indexes in the smelting and spheroidizing inoculation process, controls each link in the spheroidizing process in a timing and quantitative way, so that spheroidized raw materials are more uniform, the cast nodular manhole cover has high toughness and good wear resistance, solves the problems that the prior art requires higher content of carbon and silicon than gray cast iron in the original molten iron, reduces the content of manganese, phosphorus and sulfur in the nodular cast iron, has higher tapping temperature of the molten iron than the gray cast iron so as to compensate the loss of the molten iron temperature during spheroidizing, performs spheroidizing treatment, namely adds a spheroidizing agent into the molten iron, adds an inoculant for inoculation, needs higher casting temperature and larger casting system size, the riser and the chilling block are reasonably applied, the principle of sequential solidification is adopted, heat treatment is carried out, and the produced well lid has the problems of poor toughness and low wear resistance.

Detailed Description

The invention is described in detail below, and a smelting and spheroidizing inoculation process for manhole cover casting comprises the following operation steps: step S1, preparing raw materials; step S2, core making; step S3, sand mulling and modeling; step S4, smelting; step S5, spheroidizing inoculation; step S6, casting; step S7, vibrating and cleaning sand; step S8, shot blasting and polishing; step S1: preparing iron materials to be cast according to a certain proportion; step S2: correctly installing a core making mold on a core making machine, adding precoated sand with the granularity meeting the requirement into a sand hopper, starting the core making machine, starting manual (automatic) operation when the temperature of the mold is heated to 200 ℃, and enabling the precoated sand to enter the mold from the hopper; removing a blank on the sand core after the sand core of the well cover is demoulded; step S3: putting quartz sand, bentonite and coal powder into a sand mixer according to a certain proportion, and integrally molding the sand-mixed material and the well cover sand core in the step S2 for later use; step S4: putting the iron material to be cast prepared in the step S1 into a smelting furnace for smelting and tapping; step S5: spheroidizing inoculation is carried out on the molten iron produced in the step S4, the newly repaired molten iron ladle must be scalded when the standing time exceeds 30min before the first use and the production process, the molten iron amount in the ladle must be more than 2/3 of the ladle capacity during ladle scalding, the nodulizer is placed into a dam of the molten iron ladle according to the required molten iron amount before tapping, ferrosilicon is added on the dam and tamped, scrap iron is added for covering, the scrap iron is dried and cleaned, and the adding amount of the nodulizer is adjusted according to the actual requirement; the adding amount of the ferrosilicon is adjusted according to actual needs, the ladle is lifted into a tapping hole, when the ladle is stable and the position is proper, after the temperature of the molten iron meets the requirement, all the molten iron is quickly poured into the ladle at one time, the error of the molten iron amount is allowed to be 0-310kg, the spheroidization reaction time is 60-90S, a slag conglomeration agent is added into the ladle after the spheroidization reaction is stable, scum is completely stirred, slagging is carried out for 1-3 times per ladle of molten iron, a triangular sample is taken before a casting furnace after slagging is finished, the spheroidization condition is quickly judged, a spectrum sample is taken for each ladle to carry out chemical component analysis, the process of spheroidization inoculation requires that the chemical components of the molten iron are strictly controlled to meet the process requirement, particularly the sulfur content in the molten iron is; step S6: preheating a pouring ladle, pouring quantitative molten iron, cleaning impurities in a ladle nozzle, preventing the impurities from flowing into a product, keeping the ladle nozzle and a pouring gate at a certain height, controlling the flow of the molten iron to be smaller and gradually increased when pouring is started, and estimating that the flow of the molten iron is reduced until the molten iron in a sprue rises to a specified height when the molten iron pouring casting is quickly filled, wherein the whole process cannot cut off the flow so as to avoid cold shut of the casting; step S7: after the product is poured, cleaning the molding sand on the surface of the casting by using a high-frequency vibration shakeout machine, and knocking the sticky sand on the surface of the casting by using an iron hammer; step S8: the casting continues to enter a closed shot blasting machine along with a transmission device to treat bonded sand on the surface of the casting, the casting after shot blasting is automatically accumulated into a transfer hopper, the casting after shot blasting is lifted to a designated semi-finished product area by a crane, in the step S1, the iron material to be cast comprises 90-100% of scrap steel and 0-10% of recycled iron, in the step S2, the curing time of the well cover sand core is 80S, the sand shooting pressure is generally 0.15-0.4Mpa, the sand shooting time is 3-155S, in the step S3, the sand mixing time is more than or equal to 3min, and after 15S of wet mixing of new sand, old sand and water, bentonite, coal powder and additives are added, 120-150S of mixing is carried out, and wet molding sand is formed by mixing; the sand mixing time is not too long, otherwise, the heat generation of sand reduces the fluidity, the strength is influenced, the quality requirement of the green sand is that in order to ensure the integrity of the sand mold in the processes of drawing, running, core setting, mold closing and the like, the wet compression strength requirement is 150-200 Kpa, the air permeability is 90-160 mm/S, and the compaction rate is 32% -40%, in the step S4, a sample is required to be sampled for chemical analysis before tapping, tapping is prepared after the analysis result is obtained, in the step S5, the triangular fracture is silver gray, the structure is fine, the center has an unobvious shrinkage cavity, the tapping sound is clear and crisp, the spheroidization proves good, and in the step S5, the amount of the added scrap iron is suitable for starting to react in a bag when the molten iron is tapped to one third; the positions of the nodulizer and the ferrosilicon in the foundry ladle can be determined according to the use condition, when the bottom of one side of the foundry ladle glows, the foundry ladle can be placed on the other side of the foundry ladle, the two sides of the foundry ladle are stacked in turn, and when the temperature of the bottom of the foundry ladle is high, the nodulizer and the ferrosilicon cannot be poured into the foundry ladle too early and need to be poured into the foundry ladle before tapping; when the slag hanging of the foundry ladle is too thick, the ladle is replaced, in the step S6, the pouring temperature is 1400-1430 ℃, in order to prevent inoculation recession, spheroidized molten iron is poured within less than or equal to 15min after inoculation, in the step S8, a grinding wheel needs to be reasonably used in the grinding process, and the surface loss of the casting is prevented.

The implementation scheme is characterized by comprising the following operation steps: step S1, preparing raw materials; step S2, core making; step S3, sand mulling and modeling; step S4, smelting; step S5, spheroidizing inoculation; step S6, casting; step S7, vibrating and cleaning sand; step S8, shot blasting and polishing; step S1: preparing iron materials to be cast according to a certain proportion; step S2: correctly installing a core making mold on a core making machine, adding precoated sand with the granularity meeting the requirement into a sand hopper, starting the core making machine, starting manual (automatic) operation when the temperature of the mold is heated to 200 ℃, and enabling the precoated sand to enter the mold from the hopper; removing a blank on the sand core after the sand core of the well cover is demoulded; step S3: putting quartz sand, bentonite and coal powder into a sand mixer according to a certain proportion, and integrally molding the sand-mixed material and the well cover sand core in the step S2 for later use; step S4: putting the iron material to be cast prepared in the step S1 into a smelting furnace for smelting and tapping; step S5: spheroidizing inoculation is carried out on the molten iron produced in the step S4, the newly repaired molten iron ladle must be scalded when the standing time exceeds 30min before the first use and the production process, the molten iron amount in the ladle must be more than 2/3 of the ladle capacity during ladle scalding, the nodulizer is placed into a dam of the molten iron ladle according to the required molten iron amount before tapping, ferrosilicon is added on the dam and tamped, scrap iron is added for covering, the scrap iron is dried and cleaned, and the adding amount of the nodulizer is adjusted according to the actual requirement; the adding amount of the ferrosilicon is adjusted according to actual needs, the ladle is lifted into a tapping hole, when the ladle is stable and the position is proper, after the temperature of the molten iron meets the requirement, all the molten iron is quickly poured into the ladle at one time, the error of the molten iron amount is allowed to be 0-310kg, the spheroidization reaction time is 60-90S, a slag conglomeration agent is added into the ladle after the spheroidization reaction is stable, scum is completely stirred, slagging is carried out for 1-3 times per ladle of molten iron, a triangular sample is taken before a casting furnace after slagging is finished, the spheroidization condition is quickly judged, a spectrum sample is taken for each ladle to carry out chemical component analysis, the process of spheroidization inoculation requires that the chemical components of the molten iron are strictly controlled to meet the process requirement, particularly the sulfur content in the molten iron is; step S6: preheating a pouring ladle, pouring quantitative molten iron, cleaning impurities in a ladle nozzle, preventing the impurities from flowing into a product, keeping the ladle nozzle and a pouring gate at a certain height, controlling the flow of the molten iron to be smaller and gradually increased when pouring is started, and estimating that the flow of the molten iron is reduced until the molten iron in a sprue rises to a specified height when the molten iron pouring casting is quickly filled, wherein the whole process cannot cut off the flow so as to avoid cold shut of the casting; step S7: after the product is poured, cleaning the molding sand on the surface of the casting by using a high-frequency vibration shakeout machine, and knocking the sticky sand on the surface of the casting by using an iron hammer; step S8: the casting continues to enter a closed shot blasting machine along with transmission equipment to treat the bonded sand on the surface of the casting, the casting after shot blasting is automatically accumulated in a transfer hopper, and the casting after shot blasting is hung to a designated semi-finished product area by a crane; the smelting and spheroidizing inoculation process for the inspection well lid casting improves the existing casting process, improves various indexes in the smelting and spheroidizing inoculation process, controls each link in the spheroidizing process in a timing and quantitative manner, ensures that raw materials after spheroidizing are more uniform, further ensures that the cast nodular well lid has high toughness and good wear resistance, solves the problems that in the prior art, the content of carbon and silicon required by the original iron liquid is higher than that of gray cast iron, reduces the content of manganese, phosphorus and sulfur in the nodular cast iron, has higher tapping temperature of the iron liquid than that of gray cast iron so as to compensate spheroidizing, loss of the temperature of the iron liquid during inoculation, carries out spheroidizing, namely, nodulizing agent is added into the iron liquid, inoculant is added for inoculation, higher pouring temperature and larger size of a pouring system are required, a riser is reasonably applied, cold iron is subjected to heat treatment by adopting a sequential solidification principle, the produced well lid has the problems of poor toughness and low wear resistance.