A production process of green valve ball-milled cast iron parts

Abstract

The invention discloses a production process of a green valve spheroidal milled iron casting, and the technical scheme is as follows: comprising the following specific steps: S1, smelting preparation; S2, spheroidization treatment; S3, valve mold design and use; S4, pouring: injecting smelted molten iron into the mold through the riser of the mold, controlling the pouring temperature at 1530-1580°C, adding a heat preservation agent after the molten iron in the riser rises to two-fifths of the height during pouring, until the molten iron in the riser is full, and the time from the completion of the spheroidization treatment to the end of pouring shall not exceed 15 minutes; S5, casting cleaning; S6, annealing; S7, polishing and grinding. The invention has the beneficial effects of adopting a three-in-one mold design and related supporting production processes, the process is simple, easy to operate, saving materials, producing qualified valve castings, reducing production costs, and at the same time the production process is green and environmentally friendly, reducing environmental pollution, multiple heat-insulating risers, avoiding the occurrence of shrinkage cavities, improving product quality, and improving high temperature resistance, wear resistance and corrosion resistance.

Description

Technical Field

[0001] The invention relates to the technical field of valve cast iron production, and in particular to a production process of green valve ball-milled cast iron. Background Art

[0002] Valves are control components in fluid conveying systems and have functions such as shutoff, regulation, flow diversion, backflow prevention, pressure stabilization, diversion or overflow pressure relief. Valves used in fluid control systems come in a wide variety of varieties and specifications, from the simplest shut-off valves to the various valves used in extremely complex automatic control systems. Valves can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, mud, oil, liquid metal and radioactive media. Valves are also divided into cast iron valves, cast steel valves, stainless steel valves, chrome-molybdenum steel valves, chrome-molybdenum-vanadium steel valves, duplex steel valves, plastic valves, non-standard customized valve materials, etc.

[0003] The existing valve production process will cause environmental pollution, the valve production process is complex, the production cost is high, the production quality is low, it is easy to produce shrinkage holes, and the high temperature resistance, wear resistance and corrosion resistance are low. Summary of the invention

[0004] To this end, the present invention provides a production process for green valve spheroidal milled cast iron parts to solve the problems of environmental pollution caused by the valve production process, complex valve production process, high production cost, low production quality, easy to produce shrinkage holes, and low high temperature resistance, wear resistance and corrosion resistance.

[0005] In order to achieve the above object, the present invention provides the following technical solution: a production process of green valve ball-milled cast iron parts, the specific steps are as follows:

[0006] S1. Melting preparation:

[0007] A. Charge selection: Collect scrap steel and remove rust. After the rust removal is completed, cut the scrap steel into small pieces and put the small pieces of scrap steel into a drying oven for drying. The drying time is controlled within 30-40 minutes. Select Q12 pig iron as the raw material and cut the pig iron into small pieces for standby use.

[0008] B. Nodulizer selection: Choose rare earth magnesium ferrosilicon nodulizer;

[0009] C. Component selection: Prepare the components C 3.5-4.2%, Mn 2.3-2.7%, S 0.5-0.8%, P0.2-0.5%, Ni0.5-1.2%, Cr0.5-1.3% before smelting;

[0010] S2, spheroidizing treatment: small pieces of scrap steel and pig iron are added into the medium frequency furnace for smelting. During the smelting process, the relevant metals containing the components are added into the medium frequency furnace in the order of the shrinkage rate of the alloy elements from high to low. A smoke hood is set up on the top of the medium frequency furnace. After the molten iron is melted, the temperature is raised to 1560-1590℃ and heated for 5-10min. Then the temperature is adjusted to 1420-1470℃ and overheated for 6-10min, and the slag is removed from the furnace. The wire feeding method is used for spheroidizing and inoculation treatment. The treatment temperature is 1340-1370℃, and a spheroidizing agent is added. The spheroidizing core wire uses a high-magnesium spheroidizing wire, and the inoculation core wire uses a ferrosilicon alloy inoculation wire. After the spheroidizing treatment, wood ash is added to the surface of the molten iron to collect slag and keep warm. When pouring, the furnace door is opened and the gas is extracted through the fan on the top of the smoke hood for purification and filtration to reduce environmental pollution;

[0011] S3. Valve mold design and use: adopt a three-in-one mold design. The shape of the valve workpiece is determined by the middle mold core. The bottom mold and the mold core are combined into a valve body cavity. The top mold is provided with a riser. The three-in-one mold is assembled to form the internal runner. The runner is connected to the riser. At the same time, the mold is provided with an exhaust channel, which is connected to the exhaust pipe, and the exhaust pipe is connected to the activated carbon filter. The three-in-one mold is assembled and molded with a pressing block. After the mold is closed, casting can be carried out;

[0012] S4. Pouring: The smelted molten iron is injected into the mold through the riser of the mold. The pouring temperature is controlled at 1530-1580℃. When pouring, the heat preservation agent is added after the molten iron in the riser rises to two-fifths of the height, until it is full. The time from the completion of spheroidization to the end of pouring shall not exceed 15 minutes;

[0013] S5. Casting cleaning: After the valve casting is poured, keep it in the mold for 36-48 hours before opening the mold. First, clean the outer surface of the valve casting, then cut off the pouring and riser, and use a dry sandblasting machine to spray diamond sand on the valve casting to remove surface defects.

[0014] S6, Annealing: After cleaning the valve body, annealing is carried out. The valve casting is heated to 540-560℃, cooled in the furnace to a suitable temperature, and then air-cooled out of the furnace, followed by shot blasting;

[0015] S7. Polishing and grinding: Polishing and grinding are performed by a polishing machine.

[0016] Preferably, in step S1, Q10-Q12 pig iron can be used as the raw material.

[0017] Preferably, in step S2, before the spheroidizing treatment, the spheroidizing agent is first placed in a drying kiln for drying, the drying temperature is controlled at 100-130° C., and the temperature is kept at 100-130° C. for 2 hours.

[0018] Preferably, in step S3, 8 insulating risers are provided to effectively compensate for shrinkage.

[0019] Preferably, in step S4, the mold is dried before pouring, the drying temperature is 100-120° C., and the drying time is 30 minutes.

[0020] Preferably, in step S5, the valve casting cannot be damaged when the riser is cut off, and sufficient machining margin is left to ensure that there is sufficient machining margin.

[0021] Preferably, in step S6, the valve casting is kept warm for 6-9 hours during annealing.

[0022] The embodiments of the present invention have the following advantages:

[0023] The three-in-one mold design and its related supporting production process are simple, easy to operate, save materials, produce qualified valve castings, and reduce production costs. At the same time, the production process is green and environmentally friendly, reducing environmental pollution. Multiple insulation risers can avoid shrinkage holes, improve product quality, and improve high temperature resistance, wear resistance and corrosion resistance. Implementation

[0024] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example

[0025] The present invention provides a production process of a green valve ball-milled cast iron part, 1. The specific steps are as follows:

[0026] S1. Melting preparation:

[0027] A. Charge selection: Collect scrap steel and remove rust. After the rust removal is completed, cut the scrap steel into small pieces and put the small pieces of scrap steel into a drying oven for drying. The drying time is controlled within 30-40 minutes. Select Q12 pig iron as the raw material and cut the pig iron into small pieces for standby use. Q10-Q12 pig iron can be used as the raw material.

[0028] B. Nodulizer selection: Choose rare earth magnesium ferrosilicon nodulizer;

[0029] C. Component selection: Prepare the components C 3.5%, Mn 2.3%, S 0.5%, P 0.2%, Ni0.5%, Cr0.5% before smelting;

[0030] S2. Spheroidizing treatment: Add small pieces of scrap steel and pig iron into the medium frequency furnace for smelting. During the smelting process, the relevant metals containing the components are added into the medium frequency furnace in the order of the shrinkage rate of the alloy elements from high to low. A smoking hood is set up on the top of the medium frequency furnace. After the molten iron is melted, the temperature is raised to 1560-1590℃ and heated for 5-10min. Then the temperature is adjusted to 1420-1470℃ and overheated for 6min, and the slag is removed from the furnace. The wire feeding method is used for spheroidizing and inoculation. Treatment, the treatment temperature is 1340-1370℃, and spheroidizing agent is added. The spheroidizing core wire uses high magnesium spheroidizing wire, and the inoculating core wire uses ferrosilicon alloy inoculating wire. After spheroidizing treatment, plant ash is added to the surface of the molten iron to collect slag and keep warm. When pouring, the furnace door is opened and the gas is extracted and purified and filtered by the fan on the top of the smoke hood to reduce environmental pollution. Before spheroidizing treatment, the spheroidizing agent is first placed in a drying kiln for drying. The drying temperature is controlled at 100-130℃ and kept warm for 2h.

[0031] S3. Valve mold design and use: The three-in-one mold design is adopted. The shape of the valve workpiece is determined by the mold core in the middle. The bottom mold and the mold core are combined into the valve body cavity. The top mold is provided with a riser. The three-in-one mold is assembled to form the internal runner. The runner is connected to the riser. At the same time, the mold is provided with an exhaust channel, which is connected to the exhaust pipe, and the exhaust pipe is connected to the activated carbon filter. The three-in-one mold is assembled and molded with a pressing block. After the mold is closed, casting can be carried out. 8 heat-insulating risers are set for effective shrinkage compensation.

[0032] S4, pouring: inject the smelted molten iron into the mold through the riser of the mold, and control the pouring temperature at 1530-1580℃. When pouring, add the heat preservation agent after the molten iron in the riser rises to two-fifths of the height, and then pour it until it is full. The time from the completion of spheroidization to the end of pouring shall not exceed 15min. Dry the mold before pouring, the drying temperature is 100-120℃, and the drying time is 30min;

[0033] S5. Casting cleaning: After the valve casting is poured, the insulation time in the mold reaches 36 hours before the mold is opened. First, clean the outer surface of the valve casting, then cut off the pouring riser, and use a dry sandblasting machine to spray diamond sand on the valve casting to remove surface defects. When cutting off the riser, the valve casting must not be damaged, and sufficient processing allowance must be left here;

[0034] S6, Annealing: After cleaning the valve body, anneal it. Heat the valve casting to 540-560℃. Keep the valve casting warm for 6-9 hours during annealing. Cool it to a suitable temperature in the furnace and then air cool it. Then, perform shot blasting.

[0035] S7. Polishing and grinding: Polishing and grinding are performed by a polishing machine. Example

[0036] The present invention provides a production process of a green valve ball-milled cast iron part, 1. The specific steps are as follows:

[0037] S1. Melting preparation:

[0038] A. Charge selection: Collect scrap steel and remove rust. After the rust removal is completed, cut the scrap steel into small pieces and put the small pieces of scrap steel into a drying oven for drying. The drying time is controlled within 30-40 minutes. Select Q12 pig iron as the raw material and cut the pig iron into small pieces for standby use. Q10-Q12 pig iron can be used as the raw material.

[0039] B. Nodulizer selection: Choose rare earth magnesium ferrosilicon nodulizer;

[0040] C. Component selection: Prepare the components C 3.9%, Mn 2.5%, S 0.6%, P 0.3%, Ni 0.8%, Cr 0.9% before smelting;

[0041] S2. Spheroidizing treatment: Add small pieces of scrap steel and pig iron into the medium frequency furnace for smelting. During the smelting process, add the relevant metals containing ingredients into the medium frequency furnace in the order of alloy element shrinkage from high to low. Set up a smoking hood on the top of the medium frequency furnace. After the molten iron is melted, heat it to 1560-1590℃ and heat it for 5-10min. Then adjust the temperature to 1420-1470℃ and overheat it for 8min. Then remove the slag and take it out of the furnace. Use the wire feeding method for spheroidizing and inoculation Treatment, the treatment temperature is 1340-1370℃, and spheroidizing agent is added. The spheroidizing core wire uses high magnesium spheroidizing wire, and the inoculating core wire uses ferrosilicon alloy inoculating wire. After spheroidizing treatment, plant ash is added to the surface of the molten iron to collect slag and keep warm. When pouring, the furnace door is opened and the gas is extracted and purified and filtered by the fan on the top of the smoke hood to reduce environmental pollution. Before spheroidizing treatment, the spheroidizing agent is first placed in a drying kiln for drying. The drying temperature is controlled at 100-130℃ and kept warm for 2h.

[0042] S3. Valve mold design and use: The three-in-one mold design is adopted. The shape of the valve workpiece is determined by the mold core in the middle. The bottom mold and the mold core are combined into the valve body cavity. The top mold is provided with a riser. The three-in-one mold is assembled to form the internal runner. The runner is connected to the riser. At the same time, the mold is provided with an exhaust channel, which is connected to the exhaust pipe, and the exhaust pipe is connected to the activated carbon filter. The three-in-one mold is assembled and molded with a pressing block. After the mold is closed, casting can be carried out. 8 heat-insulating risers are set for effective shrinkage compensation.

[0043] S4, pouring: inject the smelted molten iron into the mold through the riser of the mold, and control the pouring temperature at 1530-1580℃. When pouring, add the heat preservation agent after the molten iron in the riser rises to two-fifths of the height, and then pour it until it is full. The time from the completion of spheroidization to the end of pouring shall not exceed 15min. Dry the mold before pouring, the drying temperature is 100-120℃, and the drying time is 30min;

[0044] S5. Casting cleaning: After the valve casting is poured, the insulation time in the mold reaches 42 hours before the mold is opened. First, clean the outer surface of the valve casting, then cut off the pouring riser, and use a dry sandblasting machine to spray diamond sand on the valve casting to remove surface defects. When cutting off the riser, the valve casting must not be damaged, and sufficient processing allowance must be left here;

[0045] S6, Annealing: After cleaning the valve body, anneal it. Heat the valve casting to 540-560℃. Keep the valve casting warm for 6-9 hours during annealing. Cool it to a suitable temperature in the furnace and then air cool it. Then, perform shot blasting.

[0046] S7. Polishing and grinding: Polishing and grinding are performed by a polishing machine. Example

[0047] The present invention provides a production process of a green valve ball-milled cast iron part, 1. The specific steps are as follows:

[0048] S1. Melting preparation:

[0049] A. Charge selection: Collect scrap steel and remove rust. After the rust removal is completed, cut the scrap steel into small pieces and put the small pieces of scrap steel into a drying oven for drying. The drying time is controlled within 30-40 minutes. Select Q12 pig iron as the raw material and cut the pig iron into small pieces for standby use. Q10-Q12 pig iron can be used as the raw material.

[0050] B. Nodulizer selection: Choose rare earth magnesium ferrosilicon nodulizer;

[0051] C. Component selection: Prepare the components C 4.2%, Mn 2.7%, S 0.8%, P 0.5%, Ni1.2%, Cr 1.3% before smelting;

[0052] S2. Spheroidizing treatment: Add small pieces of scrap steel and pig iron into the medium frequency furnace for smelting. During the smelting process, add the relevant metals containing ingredients into the medium frequency furnace in the order of the shrinkage rate of the alloy elements from high to low. Set up a smoking hood on the top of the medium frequency furnace. After the molten iron is melted, heat it to 1560-1590℃ and heat it for 5-10min. Then adjust the temperature to 1420-1470℃ and overheat it for 10min. Then remove the slag and take it out of the furnace. Use the wire feeding method for spheroidizing and inoculation. Treatment, the treatment temperature is 1340-1370℃, and spheroidizing agent is added. The spheroidizing core wire uses high magnesium spheroidizing wire, and the inoculating core wire uses ferrosilicon alloy inoculating wire. After spheroidizing treatment, plant ash is added to the surface of the molten iron to collect slag and keep warm. When pouring, the furnace door is opened and the gas is extracted and purified and filtered by the fan on the top of the smoke hood to reduce environmental pollution. Before spheroidizing treatment, the spheroidizing agent is first placed in a drying kiln for drying. The drying temperature is controlled at 100-130℃ and kept warm for 2h.

[0053] S3. Valve mold design and use: The three-in-one mold design is adopted. The shape of the valve workpiece is determined by the mold core in the middle. The bottom mold and the mold core are combined into the valve body cavity. The top mold is provided with a riser. The three-in-one mold is assembled to form the internal runner. The runner is connected to the riser. At the same time, the mold is provided with an exhaust channel, which is connected to the exhaust pipe, and the exhaust pipe is connected to the activated carbon filter. The three-in-one mold is assembled and molded with a pressing block. After the mold is closed, casting can be carried out. 8 heat-insulating risers are set for effective shrinkage compensation.

[0054] S4, pouring: inject the smelted molten iron into the mold through the riser of the mold, and control the pouring temperature at 1530-1580℃. When pouring, add the heat preservation agent after the molten iron in the riser rises to two-fifths of the height, and then pour it until it is full. The time from the completion of spheroidization to the end of pouring shall not exceed 15min. Dry the mold before pouring, the drying temperature is 100-120℃, and the drying time is 30min;

[0055] S5. Casting cleaning: After the valve casting is poured, the insulation time in the mold reaches 48 hours before the mold is opened. First, clean the outer surface of the valve casting, then cut off the pouring riser, and use a dry sandblasting machine to spray diamond sand on the valve casting to remove surface defects. When cutting off the riser, the valve casting must not be damaged, and sufficient processing allowance must be left here;

[0056] S6, Annealing: After cleaning the valve body, anneal it. Heat the valve casting to 540-560℃. Keep the valve casting warm for 6-9 hours during annealing. Cool it to a suitable temperature in the furnace and then air cool it. Then, perform shot blasting.

[0057] S7. Polishing and grinding: Polishing and grinding are performed by a polishing machine.

[0058] The production processes of the above embodiments 1-3 were respectively used to test the high temperature resistance, wear resistance and corrosion resistance of the valve, and the following data were obtained:

[0059]

[0060] It can be seen from the above table that Example 3 has high resistance to high temperature, wear and corrosion.

[0061] The above is only a preferred embodiment of the present invention. Any person skilled in the art may modify the present invention by using the above technical solution or modify it into an equivalent technical solution. Therefore, any simple modification or equivalent replacement made according to the technical solution of the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A production process for green valve ball-milled cast iron parts, characterized by: The specific steps are as follows: S1. Melting preparation: A. Charge selection: Collect scrap steel and remove rust. After the rust removal is completed, cut the scrap steel into small pieces and put the small pieces of scrap steel into a drying oven for drying. The drying time is controlled within 30-40 minutes. Select Q12 pig iron as the raw material and cut the pig iron into small pieces for standby use. B. Nodulizer selection: Choose rare earth magnesium ferrosilicon nodulizer; C. Component selection: Prepare the components C 3.5-4.2%, Mn 2.3-2.7%, S 0.5-0.8%, P 0.2-0.5%, Ni0.5-1.2%, Cr0.5-1.3% before smelting; S2. Spheroidizing treatment: small pieces of scrap steel and pig iron are added into the medium frequency furnace for smelting. During the smelting process, the relevant metals containing the components are added into the medium frequency furnace in the order of the shrinkage rate of the alloy elements from high to low. A smoking hood is set up on the top of the medium frequency furnace. After the molten iron is melted, the temperature is raised to 1560-1590℃ and heated for 5-10min. Then the temperature is adjusted to 1420-1470℃ and overheated for 6-10min, and the slag is removed from the furnace. The wire feeding method is used for spheroidizing and impregnation. Inoculation treatment, the treatment temperature is 1340-1370℃, and spheroidizing agent is added. The spheroidizing core wire uses high magnesium spheroidizing wire, and the inoculation core wire uses ferrosilicon alloy inoculation wire. After spheroidizing treatment, plant ash is added to the surface of the molten iron to collect slag and keep warm. When pouring, the furnace door is opened and the gas is extracted and purified and filtered by the fan on the top of the smoke hood to reduce environmental pollution. Before spheroidizing treatment, the spheroidizing agent is first placed in a drying kiln for drying. The drying temperature is controlled at 100-130℃ and kept warm for 2h; S3. Valve mold design and use: The three-in-one mold design is adopted. The shape of the valve workpiece is determined by the mold core in the middle. The bottom mold and the mold core are combined into the valve body cavity. The top mold is provided with a riser. The three-in-one mold is assembled to form the internal runner. The runner is connected to the riser. At the same time, the mold is provided with an exhaust channel, which is connected to the exhaust pipe, and the exhaust pipe is connected to the activated carbon filter. The three-in-one mold is assembled and molded with a pressing block. After the mold is closed, pouring is carried out. 8 heat-insulating risers are set for effective shrinkage compensation. S4. Pouring: The smelted molten iron is injected into the mold through the riser of the mold. The pouring temperature is controlled at 1530-1580℃. When pouring, the heat preservation agent is added after the molten iron in the riser rises to two-fifths of the height, until it is full. The time from the completion of spheroidization to the end of pouring shall not exceed 15 minutes; S5. Casting cleaning: After the valve casting is poured, keep it in the mold for 36-48 hours before opening the mold. First, clean the outer surface of the valve casting, then cut off the pouring head, and use a dry sandblasting machine to spray diamond sand on the valve casting to remove surface defects. Dry the mold before pouring at a drying temperature of 100-120℃ for 30 minutes. S6, Annealing: After the valve body is cleaned, annealing is carried out. The valve casting is heated to 540-560℃, cooled in the furnace to a suitable temperature, and then air-cooled out of the furnace, followed by shot blasting; S7. Polishing and grinding: Polishing and grinding are performed by a polishing machine.

2. The production process of a green valve ball-milled iron casting according to claim 1 is characterized in that: In step S5, the valve casting must not be damaged when the riser is cut off, and sufficient machining margin is left to ensure that there is sufficient machining margin.

3. The production process of green valve ball-milled iron casting according to claim 1 is characterized in that: In step S6, the valve casting is kept warm for 6-9 hours during annealing.

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