CN117123733B - Method for producing ductile cast iron pipe fitting under clay wet sand process condition - Google Patents
Method for producing ductile cast iron pipe fitting under clay wet sand process conditionInfo
- Publication number
- CN117123733B CN117123733B CN202311217085.4A CN202311217085A CN117123733B CN 117123733 B CN117123733 B CN 117123733B CN 202311217085 A CN202311217085 A CN 202311217085A CN 117123733 B CN117123733 B CN 117123733B
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- Prior art keywords
- molten iron
- casting
- iron
- spheroidizing
- inspection
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/02—Sand moulds or like moulds for shaped castings
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/22—Moulds for peculiarly-shaped castings
- B22C9/24—Moulds for peculiarly-shaped castings for hollow articles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/10—Making spheroidal graphite cast-iron
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C37/00—Cast-iron alloys
- C22C37/04—Cast-iron alloys containing spheroidal graphite
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C37/00—Cast-iron alloys
- C22C37/10—Cast-iron alloys containing aluminium or silicon
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Abstract
The invention provides a method for producing a ductile cast iron pipe fitting under clay wet sand process conditions, and relates to the technical field of ductile cast iron pipe fitting production processes. The method comprises the following steps of S1, preparing raw materials of pig iron, scrap steel, a furnace return material, ferrosilicon and silicon carbide in proportion, S2, smelting, namely, putting the raw materials into a medium-frequency electric furnace for smelting, S3, inoculating primary molten iron, namely, putting a primary inoculant into a tapping trough for primary inoculation when the molten iron is tapped, S4, spheroidizing, namely, enabling an automatic wire feeder to enter the molten iron according to a certain feeding speed and a spheroidizing line length for spheroidizing the molten iron, and leaving a spheroidizing station after the residual amount of magnesium and the residual amount of rare earth in the molten iron reach a specified range, S5, carrying out secondary inoculation, S6, pouring, S7, cooling and shakeout. The invention solves the technical problem that cementite and pearlite exceed standard, the elongation can reach the technological regulation requirement, and the invention has good machining performance in the as-cast state.
Description
Technical Field
The invention relates to the technical field of spheroidal graphite cast iron pipe fitting production processes, in particular to a method for producing spheroidal graphite cast iron pipe fittings under clay wet sand process conditions.
Background
The current casting or mechanical design literature in China prescribes that the minimum allowable wall thickness of sand casting ductile iron castings (the maximum outline dimension of castings is less than 200 mm) is 3-4 mm. Therefore, the existing casting of castings with the main wall thickness of 2.4-3.4 mm, especially castings used in the as-cast state under the clay wet sand process condition, brings great technical challenges.
The sand casting is divided into three processes of clay wet sand, clay dry sand and chemical hardening sand, and the cooling speed of the clay wet sand process is faster than that of the other two processes, so that the tissue and performance of the casting are more difficult to control. The technical difficulty of mass production of castings used in 2.4-3.4 mm thick casting state under the clay wet sand process condition is that:
1. Cementite is very easy to exceed standard (less than or equal to 1%), pearlite is very easy to exceed standard (less than or equal to 40%), and elongation is difficult to meet process regulation requirements (process regulation is more than or equal to 12%).
Disclosure of Invention
The invention aims to provide a method for producing ductile cast iron pipe fittings under clay wet sand process conditions, which can solve the technical problem that cementite and pearlite exceed standards by aiming at the defects of the prior art, has stable casting performance and reaches the standard, and has good machining performance in an as-cast state.
The invention adopts the technical scheme that:
the embodiment of the application provides a method for producing ductile cast iron pipe fittings under clay wet sand process conditions, which comprises the following steps:
s1, proportioning:
Raw materials of pig iron, scrap steel, a furnace return material, ferrosilicon and silicon carbide are prepared according to the following weight proportion, wherein the carbon accounts for 3.85 percent, the silicon accounts for 2.12 percent, the manganese accounts for less than or equal to 0.2 percent, the sulfur accounts for less than or equal to 0.02 percent, and the phosphorus accounts for less than or equal to 0.05 percent;
S2, smelting:
Placing the prepared raw materials of pig iron, scrap steel, furnace returns, ferrosilicon and silicon carbide into a medium frequency electric furnace for melting, and pretreating molten iron in the furnace, wherein after the temperature of the molten iron reaches 1560 ℃ and chemical components are qualified, the molten iron can be discharged from the furnace;
S3, primary molten iron inoculation:
when the molten iron is discharged, a primary inoculant is placed in a tapping trough to perform primary inoculation on the molten iron;
S4, spheroidizing:
Conveying the primary inoculated molten iron to a spheroidizing station, enabling an automatic wire feeder to enter the molten iron according to a certain feeding speed and a spheroidizing line length to spheroidize the molten iron, and enabling the magnesium residue and the rare earth residue in the molten iron to reach a specified range and then leave the spheroidizing station;
S5, secondary inoculation:
Pouring molten iron from the spheroidizing station into a ladle of a casting machine, adding a secondary inoculant along with molten iron flow while pouring the molten iron, and carrying out secondary inoculation treatment on the molten iron;
S6, pouring:
the secondary inoculation molten iron is automatically poured into a cavity made of clay wet sand through a pouring machine, and the tertiary inoculant is added into the molten iron along with molten iron flow when the secondary inoculation molten iron is poured into a sand mold cavity;
s7, cooling and shakeout:
After the poured sand mould stays for a certain time, sand-iron separation, namely cooling and shakeout are carried out, sand enters a sand treatment system for secondary utilization, and the poured casting enters the casting and a casting head enters a separation work part.
Further, in some embodiments of the present invention, after the cooling and shakeout, the method further includes the following steps:
S8, casting inspection:
and separating the casting from the casting head, and enabling the casting head and the waste casting to enter a conveying system for secondary utilization, and warehousing the casting qualified by inspection.
Further, in some embodiments of the present invention, after the casting inspection, the method further includes the following steps:
S9, surface cleaning and secondary inspection:
polishing the surface of the casting in a shot blasting machine, and performing secondary inspection on the polished casting.
Further, in some embodiments of the present invention, the method further comprises the following steps after the surface cleaning and the secondary inspection:
s10, hot galvanizing:
The casting after the secondary inspection enters a hot galvanizing work part to carry out surface galvanizing on the casting;
S11, machining:
Carrying out plain end and threading on the casting after hot galvanizing;
s12, final inspection packaging:
And (5) inspecting the machined castings, and packaging and warehousing products after the inspection is qualified.
Further, in some embodiments of the present invention, the primary inoculant includes a silicon-calcium alloy and silicon carbide, wherein the silicon-calcium alloy is 0.3% by weight relative to the molten iron and the silicon carbide is 0.2% by weight relative to the molten iron.
Further, in some embodiments of the present invention, the specified ranges of the magnesium residual amount and the rare earth residual amount in the molten iron during the spheroidizing process are that the magnesium residual amount accounts for 0.025-0.035% of the weight of the molten iron, and the rare earth residual amount accounts for 0.008-0.015% of the weight of the molten iron.
Further, in some embodiments of the present invention, the secondary inoculant comprises a silicon-calcium-barium alloy, wherein the silicon-calcium-barium alloy accounts for 0.4-0.6% of the weight of molten iron;
the triple inoculant comprises a silicon-calcium-barium alloy at the time of casting, wherein the weight ratio of the silicon-calcium-barium alloy relative to molten iron is 0.15 percent.
Further, in some embodiments of the present invention, the weight ratio of the carbon equivalent in the molten iron to the molten iron is controlled to be 4.6-4.7% during the pouring.
Further, in some embodiments of the present invention, the silicon to carbon ratio in the molten iron is ∈0.83 during the casting.
Compared with the prior art, the embodiment of the invention has at least the following advantages or beneficial effects:
the method comprises the steps of preprocessing the base molten iron, namely adding silicon carbide into a furnace to preprocess the molten iron, purifying the molten iron and adding graphite crystal cores.
The inoculation effect is enhanced, the number of graphite nodules is greatly increased, and the primary inoculation is subjected to intensive research and multiple experiments while the secondary stream inoculation effect is improved, so that the number of graphite nodules is increased by more than 30% on the basis of the original graphite nodules by adopting a composite inoculation mode on the premise of not increasing the production cost.
The technical problem that cementite and pearlite exceed standards is solved, the elongation can meet the requirements of process regulations, the performance of castings is stable and reaches the standards, and the casting has good machining performance in an as-cast state.
Detailed Description
Examples
The embodiment provides a method for producing ductile cast iron pipe fittings under clay wet sand process conditions, which comprises the following steps:
s1, proportioning:
Raw materials of pig iron, scrap steel, a furnace return material, ferrosilicon and silicon carbide are prepared according to the following weight proportion, wherein the carbon accounts for 3.85 percent, the silicon accounts for 2.12 percent, the manganese accounts for less than or equal to 0.2 percent, the sulfur accounts for less than or equal to 0.02 percent, and the phosphorus accounts for less than or equal to 0.05 percent;
S2, smelting:
The prepared pig iron, scrap steel, furnace return materials, ferrosilicon and silicon carbide raw materials are put into a medium frequency electric furnace to be melted, the molten iron in the furnace is pretreated, and after the temperature of the molten iron reaches 1560 ℃ and the chemical components are qualified, the molten iron can be discharged from the furnace, and the molten iron is pretreated by adding silicon carbide into the furnace to purify the molten iron and increase the graphite crystal core.
S3, primary molten iron inoculation:
And when the molten iron is discharged, a primary inoculant is placed in the tapping groove to perform primary inoculation on the molten iron, wherein the primary inoculant comprises a silicon-calcium alloy and silicon carbide, the weight ratio of the silicon-calcium alloy to the molten iron is 0.3%, and the weight ratio of the silicon carbide to the molten iron is 0.2%. On the premise of not increasing the production cost, a compound inoculation mode is adopted, so that the number of graphite nodules is increased by more than 30% on the original basis.
S4, spheroidizing:
Conveying the primary inoculated molten iron to a spheroidizing station, enabling an automatic wire feeder to enter the molten iron according to a certain feeding speed and a spheroidizing line length to spheroidize the molten iron, and enabling the magnesium residue and the rare earth residue in the molten iron to reach a specified range and then leave the spheroidizing station;
Wherein the prescribed range of the magnesium residue and the rare earth residue in the molten iron is that the weight ratio of the magnesium residue to the molten iron is 0.025-0.035%, and the weight ratio of the rare earth residue to the molten iron is 0.008-0.015%.
S5, secondary inoculation:
Pouring molten iron from the spheroidizing station into a ladle of a casting machine, and adding a secondary inoculant along with molten iron flow while pouring the molten iron to perform secondary inoculation treatment on the molten iron, wherein the secondary inoculant comprises a silicon-calcium-barium alloy, and the weight ratio of the silicon-calcium-barium alloy relative to the molten iron is 0.4-0.6%;
S6, pouring:
the secondary inoculation molten iron is automatically poured into a cavity made of clay wet sand through a pouring machine, and is poured into a sand mold cavity along with molten iron flow at the same time, wherein the tertiary inoculant comprises a silicon-calcium-barium alloy, and the weight ratio of the silicon-calcium-barium alloy to the molten iron is 0.15%.
The weight ratio of the carbon equivalent in the molten iron to the molten iron is controlled to be 4.6-4.7%, and the weight ratio of the sum of one third of the weight of silicon and the weight of carbon to the molten iron is controlled. The silicon-carbon ratio in the molten iron is equal to or greater than 0.83.
S7, cooling and shakeout:
After the poured sand mould stays for a certain time, sand-iron separation, namely cooling and shakeout are carried out, sand enters a sand treatment system for secondary utilization, and the poured casting enters the casting and a casting head enters a separation work part.
S8, casting inspection:
and separating the casting from the casting head, and enabling the casting head and the waste casting to enter a conveying system for secondary utilization, and warehousing the casting qualified by inspection.
S9, surface cleaning and secondary inspection:
polishing the surface of the casting in a shot blasting machine, and performing secondary inspection on the polished casting.
S10, hot galvanizing:
The casting after the secondary inspection enters a hot galvanizing work part to carry out surface galvanizing on the casting;
S11, machining:
Carrying out plain end and threading on the casting after hot galvanizing;
s12, final inspection packaging:
And (5) inspecting the machined castings, and packaging and warehousing products after the inspection is qualified.
The method for producing the spheroidal graphite cast iron pipe fitting under the clay wet sand process condition comprises the steps of pretreating the base molten iron, adding silicon carbide into a furnace to pretreat the molten iron, purifying the molten iron and increasing graphite crystal cores.
The inoculation effect is enhanced, the number of graphite nodules is greatly increased, and the primary inoculation is subjected to intensive research and multiple experiments while the secondary stream inoculation effect is improved, so that the number of graphite nodules is increased by more than 30% on the basis of the original graphite nodules by adopting a composite inoculation mode on the premise of not increasing the production cost. The technical problem that cementite and pearlite exceed standards is solved, the elongation can meet the requirements of process regulations, the performance of castings is stable and reaches the standards, and the casting has good machining performance in an as-cast state.
The foregoing is merely a preferred embodiment of the present application, and it is not intended to limit the present application, and it will be apparent to those skilled in the art that the present application is not limited to the details of the above-described exemplary embodiment, but may be embodied in other specific forms without departing from the spirit or essential characteristics thereof.
The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (9)
1. A method for producing ductile cast iron pipe fittings under clay wet sand process conditions is characterized by comprising the following steps:
s1, proportioning:
Raw materials of pig iron, scrap steel, a furnace return material, ferrosilicon and silicon carbide are prepared according to the following weight proportion, wherein the carbon accounts for 3.85 percent, the silicon accounts for 2.12 percent, the manganese accounts for less than or equal to 0.2 percent, the sulfur accounts for less than or equal to 0.02 percent, and the phosphorus accounts for less than or equal to 0.05 percent;
S2, smelting:
Placing the prepared raw materials of pig iron, scrap steel, furnace returns, ferrosilicon and silicon carbide into a medium frequency electric furnace for melting, and pretreating molten iron in the furnace, wherein after the temperature of the molten iron reaches 1560 ℃ and chemical components are qualified, the molten iron can be discharged from the furnace;
S3, primary molten iron inoculation:
when the molten iron is discharged, a primary inoculant is placed in a tapping trough to perform primary inoculation on the molten iron;
S4, spheroidizing:
Conveying the primary inoculated molten iron to a spheroidizing station, enabling an automatic wire feeder to enter the molten iron according to a certain feeding speed and a spheroidizing line length to spheroidize the molten iron, and enabling the magnesium residue and the rare earth residue in the molten iron to reach a specified range and then leave the spheroidizing station;
S5, secondary inoculation:
Pouring molten iron from the spheroidizing station into a ladle of a casting machine, adding a secondary inoculant along with molten iron flow while pouring the molten iron, and carrying out secondary inoculation treatment on the molten iron;
S6, pouring:
the secondary inoculation molten iron is automatically poured into a cavity made of clay wet sand through a pouring machine, and the tertiary inoculant is added into the molten iron along with molten iron flow when the secondary inoculation molten iron is poured into a sand mold cavity;
s7, cooling and shakeout:
After the poured sand mould stays for a certain time, sand-iron separation, namely cooling and shakeout are carried out, sand enters a sand treatment system for secondary utilization, and the poured casting enters the casting and a casting head enters a separation work part.
2. The method for producing ductile iron pipe fittings under clay wet sand processing conditions according to claim 1 further comprising the steps of, after cooling down the shakeout:
S8, casting inspection:
and separating the casting from the casting head, and enabling the casting head and the waste casting to enter a conveying system for secondary utilization, and warehousing the casting qualified by inspection.
3. The method for producing ductile iron pipe fitting according to claim 2 further comprising the following steps after the casting inspection:
S9, surface cleaning and secondary inspection:
polishing the surface of the casting in a shot blasting machine, and performing secondary inspection on the polished casting.
4. The method for producing ductile iron pipe fittings according to claim 3 further comprising the following steps after the surface cleaning and the secondary inspection:
s10, hot galvanizing:
The casting after the secondary inspection enters a hot galvanizing work part to carry out surface galvanizing on the casting;
S11, machining:
Carrying out plain end and threading on the casting after hot galvanizing;
s12, final inspection packaging:
And (5) inspecting the machined castings, and packaging and warehousing products after the inspection is qualified.
5. The method for producing ductile iron pipe according to claim 1 wherein the primary inoculant comprises a silicon-calcium alloy and silicon carbide, wherein the weight ratio of the silicon-calcium alloy to the molten iron is 0.3% and the weight ratio of the silicon carbide to the molten iron is 0.2% when the primary molten iron is inoculated.
6. The method for producing ductile iron pipe fittings under the clay wet sand process condition according to claim 1, wherein the prescribed ranges of the magnesium residual quantity and the rare earth residual quantity in the molten iron during the spheroidization are that the weight ratio of the magnesium residual quantity to the molten iron is 0.025-0.035%, and the weight ratio of the rare earth residual quantity to the molten iron is 0.008-0.015%.
7. The method for producing ductile iron pipe fittings under the clay wet sand process condition according to claim 1 wherein the secondary inoculant comprises a Si-Ca-Ba alloy in which the weight ratio of Si-Ca-Ba alloy to molten iron is 0.4-0.6%;
the triple inoculant comprises a silicon-calcium-barium alloy at the time of casting, wherein the weight ratio of the silicon-calcium-barium alloy relative to molten iron is 0.15 percent.
8. The method for producing ductile iron pipe fittings under clay wet sand process conditions according to claim 1 wherein the weight ratio of carbon equivalent in molten iron to molten iron is controlled to be 4.6-4.7% during casting.
9. The method for producing ductile iron pipe fittings according to claim 1 wherein the Si/C ratio in the molten iron is ≡0.83 during casting.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311217085.4A CN117123733B (en) | 2023-09-20 | 2023-09-20 | Method for producing ductile cast iron pipe fitting under clay wet sand process condition |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311217085.4A CN117123733B (en) | 2023-09-20 | 2023-09-20 | Method for producing ductile cast iron pipe fitting under clay wet sand process condition |
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| CN117123733B true CN117123733B (en) | 2026-01-13 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109972025A (en) * | 2019-03-29 | 2019-07-05 | 山西中设华晋铸造有限公司 | A kind of spheroidal graphite cast-iron preparation method |
| CN113174527A (en) * | 2021-04-28 | 2021-07-27 | 山东湖西王集团铸业有限公司 | Method for producing nodular cast iron by casting green sand |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1364836A (en) * | 1970-07-02 | 1974-08-29 | Materials & Methods Ltd | Process for the manufacture of cast iron |
| JP4806477B2 (en) * | 2001-04-23 | 2011-11-02 | 東京鐵鋼株式会社 | Production method of as-cast spheroidal graphite cast iron products |
| CN102021257B (en) * | 2010-12-30 | 2012-06-20 | 安阳钢铁股份有限公司 | Casting method of nodular cast iron cooling wall with thick cross section and high elongation |
| JP5839461B2 (en) * | 2011-10-07 | 2016-01-06 | 曙ブレーキ工業株式会社 | Method for producing spheroidal graphite cast iron, and method for producing vehicle parts using spheroidal graphite cast iron |
| CN103820701B (en) * | 2014-02-11 | 2016-03-02 | 山东秋辰机械制造有限公司 | The production technique of as cast condition QT600-7 nodular iron casting |
| CN114700461A (en) * | 2022-03-09 | 2022-07-05 | 山西康腾威机械制造有限公司 | Casting method of thin-wall nodular iron casting capable of eliminating free cementite |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109972025A (en) * | 2019-03-29 | 2019-07-05 | 山西中设华晋铸造有限公司 | A kind of spheroidal graphite cast-iron preparation method |
| CN113174527A (en) * | 2021-04-28 | 2021-07-27 | 山东湖西王集团铸业有限公司 | Method for producing nodular cast iron by casting green sand |
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