CN115533040A - Casting method of high-density high-pressure-resistant nodular valve body - Google Patents
Casting method of high-density high-pressure-resistant nodular valve body Download PDFInfo
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- CN115533040A CN115533040A CN202211250979.9A CN202211250979A CN115533040A CN 115533040 A CN115533040 A CN 115533040A CN 202211250979 A CN202211250979 A CN 202211250979A CN 115533040 A CN115533040 A CN 115533040A
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- 238000005266 casting Methods 0.000 title claims abstract description 80
- 238000000034 method Methods 0.000 title claims abstract description 24
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 82
- 229910052742 iron Inorganic materials 0.000 claims abstract description 39
- 229910052761 rare earth metal Inorganic materials 0.000 claims abstract description 9
- 229910000861 Mg alloy Inorganic materials 0.000 claims abstract description 6
- 150000002910 rare earth metals Chemical class 0.000 claims abstract description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 64
- 239000004576 sand Substances 0.000 claims description 48
- 238000002844 melting Methods 0.000 claims description 12
- 230000008018 melting Effects 0.000 claims description 12
- 239000002054 inoculum Substances 0.000 claims description 11
- 238000005422 blasting Methods 0.000 claims description 10
- 238000005498 polishing Methods 0.000 claims description 6
- 229910052717 sulfur Inorganic materials 0.000 claims description 6
- APGROBRHKCQTIA-UHFFFAOYSA-N [Mg].[Si].[Fe] Chemical compound [Mg].[Si].[Fe] APGROBRHKCQTIA-UHFFFAOYSA-N 0.000 claims description 5
- 229910052799 carbon Inorganic materials 0.000 claims description 5
- 229910052698 phosphorus Inorganic materials 0.000 claims description 5
- 239000000126 substance Substances 0.000 claims description 5
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 claims description 4
- 229910000805 Pig iron Inorganic materials 0.000 claims description 4
- 238000000227 grinding Methods 0.000 claims description 4
- VKYKSIONXSXAKP-UHFFFAOYSA-N hexamethylenetetramine Chemical compound C1N(C2)CN3CN1CN2C3 VKYKSIONXSXAKP-UHFFFAOYSA-N 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 4
- 239000005011 phenolic resin Substances 0.000 claims description 4
- 229920001568 phenolic resin Polymers 0.000 claims description 4
- 229910052710 silicon Inorganic materials 0.000 claims description 4
- 239000000377 silicon dioxide Substances 0.000 claims description 4
- 238000011010 flushing procedure Methods 0.000 claims description 3
- 239000002893 slag Substances 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 2
- 238000010079 rubber tapping Methods 0.000 claims description 2
- 229910001141 Ductile iron Inorganic materials 0.000 abstract description 19
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 14
- 229910002804 graphite Inorganic materials 0.000 abstract description 13
- 239000010439 graphite Substances 0.000 abstract description 13
- 230000007797 corrosion Effects 0.000 abstract description 7
- 238000005260 corrosion Methods 0.000 abstract description 7
- 238000012545 processing Methods 0.000 abstract description 7
- 229910001208 Crucible steel Inorganic materials 0.000 abstract description 6
- 238000005520 cutting process Methods 0.000 abstract description 5
- 238000004519 manufacturing process Methods 0.000 abstract description 4
- 229910000519 Ferrosilicon Inorganic materials 0.000 abstract description 3
- 230000003647 oxidation Effects 0.000 abstract description 2
- 238000007254 oxidation reaction Methods 0.000 abstract description 2
- 230000003313 weakening effect Effects 0.000 abstract description 2
- 230000003670 easy-to-clean Effects 0.000 abstract 1
- 230000002349 favourable effect Effects 0.000 abstract 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 7
- 239000003795 chemical substances by application Substances 0.000 description 7
- 239000011777 magnesium Substances 0.000 description 7
- 229910052749 magnesium Inorganic materials 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- 238000012216 screening Methods 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 238000012360 testing method Methods 0.000 description 6
- 239000004927 clay Substances 0.000 description 5
- 150000003839 salts Chemical class 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000007769 metal material Substances 0.000 description 3
- 239000008239 natural water Substances 0.000 description 3
- 238000004080 punching Methods 0.000 description 3
- 238000005201 scrubbing Methods 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 230000005674 electromagnetic induction Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000007885 magnetic separation Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- -1 rare earth sulfide Chemical class 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 230000001502 supplementing effect Effects 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 230000007306 turnover Effects 0.000 description 2
- 238000007546 Brinell hardness test Methods 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 229910052684 Cerium Inorganic materials 0.000 description 1
- 229910020101 MgC2 Inorganic materials 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000008235 industrial water Substances 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 239000006148 magnetic separator Substances 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 229910001404 rare earth metal oxide Inorganic materials 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
Classifications
-
- 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
- B22C—FOUNDRY MOULDING
- B22C15/00—Moulding machines characterised by the compacting mechanism; Accessories therefor
- B22C15/23—Compacting by gas pressure or vacuum
- B22C15/24—Compacting by gas pressure or vacuum involving blowing devices in which the mould material is supplied in the form of loose particles
-
- 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
- C21C1/02—Dephosphorising or desulfurising
- C21C1/025—Agents used for dephosphorising or desulfurising
-
- 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
- C21C1/04—Removing impurities other than carbon, phosphorus or sulfur
-
- 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
- C21C1/105—Nodularising additive agents
-
- 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
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (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 belongs to the technical field of casting, and relates to a method for casting a high-density high-pressure resistant nodular cast iron body, which uses a rare earth ferrosilicon magnesium alloy nodulizer, has the advantages of good manufacturing manufacturability, compact structure, good rigidity, smooth passage, corrosion resistance and oxidation resistance of nodular cast iron exceeding cast steel, and because of the spherical graphite microstructure of the nodular cast iron, the method is more favorable for reducing stress in the aspect of weakening vibration capability, has low cast steel cost and higher casting efficiency, and has the advantages of low processing cost and the same wall thickness, the nodular cast iron piece is safe and economic, good casting performance and good molten iron fluidity of the nodular cast iron, can cast thin-wall and complex valve body pieces, has smooth surface of the valve body and is easy to clean, and simultaneously, the existence of the spherical graphite improves the cutting performance of the nodular cast iron, and can form brittleness when a cutter contacts the graphite, and has good cutting performance and corrosion resistance.
Description
Technical Field
The invention belongs to the technical field of casting, and particularly relates to a casting method of a high-density high-pressure-resistant nodular graphite valve body.
Background
Water supply and drainage valves are commonly used in domestic water supply, fire protection systems and industrial water supply systems. For controlling flow, water level, etc. The valve body material works below the elastic limit, the yield strength plays a leading role, and the material used for the valve body is required to have certain plasticity. On one hand, the valve body can not be frost-cracked under the condition of low temperature; on the other hand, when overpressure or deformation of connected components, such as pipes, occurs, the valve body is not damaged due to plastic deformation. The valve body belongs to a pressurized container, and the pressure resistance of the valve body material is particularly important. The general engineering metal material not only has higher yield strength, but also has a certain yield ratio. If the yield ratio is small, the structural parts have high safety reliability, i.e., the strength of the metal is increased by plastic deformation without sudden breakage in the event of overload. However, if the yield ratio is too low, the effective utilization of the material strength will be too low, so that a higher yield ratio is generally desirable. The valve body mainly bears tensile and bending loads, and allowable stress is generally determined according to yield strength during design calculation. CN201510711959.0 discloses a surface treatment method for a carbon steel valve body of a check valve, and CN201611081638.8 discloses a casting process method for a hollow valve body steel casting, but such cast steel valve body has thicker wall thickness and slightly lower safety and reliability, and therefore, the skilled in the art needs to develop a casting method for a high-density high-pressure resistant nodular graphite valve body.
Disclosure of Invention
Aiming at the problems, the invention aims to provide a casting method of a high-density high-pressure-resistant nodular graphite valve body.
The invention is realized by the following technical scheme:
a casting method of a high-density high-pressure-resistant nodular cast iron valve body comprises the following steps:
step one, core making: the precoated sand is put into a core shooting machine, the precoated sand is sent into a core shooting machine die through a pressure air pump, the die is heated to 230-250 ℃, the sand shooting pressure is 0.15-0.4 MPa, the sand shooting time is controlled to be 3-10s, and the crust forming time is controlled to be 10-30s, so that the required sand core can be obtained; second step, (1) iron melting and casting: the pig iron is manually put into a furnace body of a medium-frequency electric furnace, the medium-frequency electric furnace melts molten iron, and the chemical components of the molten iron are controlled as follows: 3.5-3.99% of C, 1.2-1.5% of Si, less than 0.06% of P, less than 0.05% of S and 45 minutes of molten iron melting time of each furnace of the medium-frequency electric furnace; (2) spheroidizing: spheroidizing by adopting a pit punching method, before spheroidizing, firstly filling a spheroidizing agent, an inoculant and the like into a special spheroidizing bag, adopting the spheroidizing bag with the height-diameter ratio of 2: 1, adding the spheroidizing agent and the inoculant into the bag according to the proportion of 1.8 percent and 0.9 percent, adding the spheroidizing agent and the inoculant into the bag, covering dry scrap iron on the nodulizing bag, completely removing surface scum, heating molten iron in a furnace to 1480-1500 ℃ for tapping, punching molten iron on one side of a casting side close to the electric furnace into the other side of the spheroidizing bag, and injecting 2/3 or 3/4 of the total amount of the spheroidizing bag at one time, wherein the spheroidizing time is controlled to be 90s-300s; and (3) casting: the ladle is transported to a casting line through a crown block, the ladle is cast in a manual casting mode, and the casting is finished within 10 to 20min, and the ladle comprises the following chemical components: 3.6 to 3.7 percent of C, 2.2 to 2.4 percent of Si, 0.2 to 0.3 percent of MnS, less than or equal to 0.02 percent of S and less than 0.05 percent of P; (4) turning over the box and shakeout: after casting, the box body is conveyed to a shakeout position along with a conveyor belt, the box is manually turned over to take out a casting, and a sand core is picked out; the clay sand after the box turning falls into the pit and is transported to a sand treatment line for treatment by a belt conveyor; thirdly, shot blasting and polishing: and after the casting is picked up, removing oxide skin and sticky sand on the surface of the casting by using a shot blasting machine, and after shot blasting, polishing the surface of the casting by using a grinding machine to ensure that the surface of the casting is smooth and flat to obtain the casting.
Further, the nodulizer is a rare earth silicon iron magnesium alloy nodulizer, and comprises the specific components of 6-8% of Ce, 7.0-8% of Mg7.0, 35-40% of Si, 2-3.5% of Ca, less than or equal to 0.5% of Ti and less than or equal to 0.5% of Al, and the balance of Fe.
Further, the inoculant is FeSi75.
Further, the precoated sand is a uniform mixture of 100% of natural water scrubbing silica sand, 1.0-3.0% of 2124 type phenolic resin, 0.5-0.7% of urotropine solution with the mass fraction of 50% and 0.005-0.01% of Wolan.
The invention has the beneficial effects that:
the invention uses rare earth silicon iron magnesium alloy nodulizer, the vapor pressure in the molten iron is high, and the molten iron is enabled to be fleas. At the temperature of molten iron treatment, the vapor pressure generated by magnesium is high, and when magnesium is added into molten iron, vaporization is generated to tumble the molten iron. Second, it has strong affinity with sulfur and oxygen. The resulting MgO and MgS have high melting points and much lower densities than iron and are easily separated from molten iron, so that the molten iron after magnesium treatment has a reduced content of sulfur and oxygen impurities and tends to segregate to graphite during solidification of the molten iron, and when the amount of the magnesium remaining in the molten iron exceeds 0.035%, the molten iron can be spheroidized, but when the amount of the magnesium remaining exceeds 0.07%, a part of magnesium segregates to grain boundaries and an exothermic reaction occurs with carbon, phosphorus and the like in the grain boundaries to produce MgC2, mg2C3, mg3P2 and the like. When the amount of residual magnesium is larger, intergranular carbides increase. The cerium rare earth element has high boiling point, does not cause the tumble and splash of molten iron when being added into the molten iron, has stronger desulfurization and deoxidation capacity, and generates compounds such as rare earth sulfide, rare earth oxide and the like with high melting point and good stability; the anti-interference capability is strong. The residual quantity of rare earth elements has obvious influence on graphite spheroidization.
Compared with the prior art, the invention has the following advantages:
the preparation method of the high-density high-pressure-resistant nodular cast iron valve body disclosed by the invention has the advantages of good manufacturing manufacturability, compact structure, good rigidity and smooth channel, and the corrosion resistance and the oxidation resistance of the nodular cast iron exceed those of cast steel in most municipal application fields such as water, salt water, steam and the like. Because of the spherical graphite microstructure of the nodular cast iron, the stress is more favorably reduced in the aspect of weakening the vibration capability. The ductile iron has lower cost than cast steel, higher casting efficiency, lower processing cost and the same wall thickness, the ductile iron casting is safe and economic, the ductile iron has better casting performance than the cast steel, the molten iron of the ductile iron has good fluidity, the ductile iron can cast thin-wall and complex valve body pieces, the surface of the valve body is smooth and easy to sand, meanwhile, the existence of the spheroidal graphite improves the cutting processing performance of the ductile iron, brittle cutting can be formed when a cutter contacts the graphite, and the ductile iron has good cutting processing performance and good corrosion resistance.
Detailed Description
The invention is illustrated by the following specific examples, which are not intended to be limiting.
Example 1
Firstly, the precoated sand is put into a transfer barrel of a vertical parting precoating ZKX-6040 core shooter through an electric single-beam crane LDA2.8-18.65A3, the precoated sand in the barrel is sent to a core shooter die through a pressure air pump, the die adopts electricity as a heat source, the die is heated to 230 ℃, the sand shooting pressure is 0.15MPa, the sand shooting time is controlled to be 3s, the crusting time is controlled to be 10s, the precoated sand is a uniform mixture of 100% of Dalin ZGS90-50/100 natural water scrubbing silica sand, 1.0% of 2124 type phenolic resin, 0.5% of urotropine solution with the mass fraction of 50% and 0.005% of olan, and the needed core body can be obtained.
Second step, iron melting and casting: a. a melting section: the method is characterized in that outsourced pig iron, low-carbon steel, ferrosilicon and the like are manually put into a furnace body of the medium-frequency electric furnace, the medium-frequency electric furnace converts three-phase power-frequency alternating current into direct current through a rectifying circuit, the direct current is output to be single-phase medium-frequency alternating current through an inverter circuit and is supplied to a medium-frequency coreless induction furnace, and then a workpiece is placed in an alternating magnetic field to generate eddy current and generate heat by utilizing the electromagnetic induction principle. The molten iron melting time of each furnace of the medium-frequency electric furnace is 45 minutes;
b. spheroidizing: the spheroidizing treatment adopts a pit punching method to carry out spheroidizing, before spheroidizing, a spheroidizing agent, an inoculant, a rare earth silicon iron magnesium alloy spheroidizing agent and the like are filled into a special spheroidizing bag, the inoculant is FeSi75, the rare earth silicon iron magnesium alloy spheroidizing agent comprises the specific components of Ce8%, mg8%, si40%, ca3.5%, ti less than or equal to 0.5%, al less than or equal to 0.5% and the balance of Fe. Pouring molten iron on one side of the casting side close to the electric furnace into the other side of the spheroidizing ladle once, injecting the molten iron into the spheroidizing ladle once by 2/3 of the total amount of the spheroidizing ladle, controlling the spheroidizing time to be 90s, supplementing the residual molten iron after the reaction is basically finished, and finally removing iron slag;
a casting section: the ladle is transported to a casting line through a crown block, the ladle is cast in a manual casting mode, the casting is finished in 10min, and the ladle is composed of the following chemical components: 3.6 percent of C, 2.2 percent of Si, 0.2 percent of Mn, less than or equal to 0.02 percent of S, less than 0.05 percent of P, and the steps of turning over and shakeout:
after casting, the box body is conveyed to a shakeout position along with a conveyor belt, the casting is taken out by manually turning the box, a sand core is picked up, and the sand core is subjected to outside treatment after being collected; the clay sand after the turnover falls into the pit and is transported to a sand treatment line for treatment by a belt conveyor.
Sand treatment: the sand processing workshop section adopts full-automatic 100t/h clay sand production line, the major process includes the dust removal, the screening, cooling and magnetic separation, the retrieval and utilization sand is transported to the screening machine through belt conveyer and is carried out the first screening, the sand after the preliminary screening gets into boiling cooling bed by the blanking fill and handles, through the mutual friction between the grit, make the grit have certain soft regeneration ability, the sand after the processing falls into belt conveyer on, transport to the screening machine through belt conveyer and carry out secondary screening processing, the sand after the screening is transported to the roller mill through belt conveyer and is carried out the mulling and handle. The mulling process is carried out by feeding through a raw material bin, water is added through a water tank, and magnetic separation is carried out through a magnetic separator after mulling, so that metal impurities in materials are removed.
And a third step of grinding: a. after the castings are shot-blasted and picked up, the oxide skin and the sand sticking on the surfaces of the castings are removed by a shot blasting machine HF6910, wherein steel shots with the conveying speed of 5m/s, the casting speed of 78m/s and the casting speed of 0.8mm are used.
b. Manual polishing: after shot blasting, the surface of the casting is polished by a grinder to be smooth and flat, and the valve body casting with the flange diameter of 660mm, the length of 640mm and the wall thickness of 15mm is obtained.
The product performance is as follows: under the condition of rated working pressure of 38Mpa, the hydraulic casting material has no phenomena of liquid seepage, air leakage and burst, and the spheroidization rate is as follows: 89 percent; grade 3 of spheroidization; graphite size: reaching grade 5; the casting method is characterized in that the casting defects influencing use are avoided due to the fact that the tensile strength is 468.3Mpa, the yield strength is 324.5Mpa, the elongation is 11.2%, the Brinell hardness is 178HB, the surface is not visible, the inner cavity surface is clean, phenomena such as residual sand, bonded sand and flash burrs are avoided, the corrosion resistance degree is subjected to a neutral salt spray test (NSS test) specified in GB/T10125-2012, and the mass loss is 118g/m 2 。
Example 2
Firstly, the precoated sand is put into a transfer barrel of a ZKX-6040 core shooting machine through an electric single-beam crane LDA2.8-18.65A3, the precoated sand is a uniform mixture of 100% of Dalin ZGS90-50/100 natural water scrubbing silica sand, 3.0% of 2124 type phenolic resin, 0.7% of urotropine solution with the mass fraction of 50% and 0.01% of Wailan in percentage by mass, the precoated sand in the barrel is sent into a core shooting machine mold through a pressure air pump, the mold adopts electricity as a heat source, the mold is heated to 250 ℃, the sand shooting pressure is 0.4MPa, the sand shooting time is controlled at 10s, and the crusting time is controlled at 30s, so that the required core can be obtained. Second step, iron melting and casting: a. a melting section: the method is characterized in that outsourced pig iron, low-carbon steel, ferrosilicon and the like are manually put into a furnace body of the medium-frequency electric furnace, the medium-frequency electric furnace converts three-phase power-frequency alternating current into direct current through a rectifying circuit, the direct current is output to be single-phase medium-frequency alternating current through an inverter circuit and is supplied to a medium-frequency coreless induction furnace, and then a workpiece is placed in an alternating magnetic field to generate eddy current and generate heat by utilizing the electromagnetic induction principle. The molten iron melting time of each furnace of the medium-frequency electric furnace is 45 minutes;
b. spheroidizing: spheroidizing by adopting a pit flushing method, firstly loading a spheroidizing agent, an inoculant and the like into a special spheroidizing bag before spheroidizing, flushing molten iron on one side of a casting side close to an electric furnace into the other side of the spheroidizing bag for one time, injecting the molten iron into the spheroidizing bag for one time by 3/4 of the total amount, controlling the spheroidizing time to be 300s, supplementing the rest molten iron after the reaction is basically finished, and finally removing iron slag;
a casting section: the ladle is transported to a casting line through a crown block, the ladle is cast in a manual casting mode, the casting is finished within 20min, and the ladle comprises the following chemical components: 3.7 percent of C, 2.4 percent of Si, 0.3 percent of MnS, less than or equal to 0.02 percent of S, less than 0.05 percent of P and the balance of Fe; and (3) turning over and shakeout:
after casting, the box body is conveyed to a shakeout position along with a conveyor belt, the casting is taken out by manually turning the box body, sand cores are picked up, and the sand cores are subjected to outside treatment after being collected; the clay sand after the turnover falls into the pit and is transported to a sand treatment line for treatment by a belt conveyor.
Sand treatment: the sand treatment section adopts a full-automatic clay sand production line of 100t/h, which is the same as that in the embodiment 1.
And step three, grinding: a. after the casting is shot-blasted and picked up, the oxide skin and the sand on the surface of the casting are removed by a shot blasting machine HF6910, wherein the steel shot with the conveying speed of 5m/s, the casting speed of 78m/s and the casting speed of 0.8 mm.
b. Manual polishing: after shot blasting, the surface of the casting is polished by a grinder to be smooth and flat, and the valve body casting with the flange diameter of 660mm, the length of 640mm and the wall thickness of 15mm is obtained.
The product performance is as follows: under the condition of rated working pressure of 38Mpa, the hydraulic casting material has no phenomena of liquid seepage, air leakage and burst, and the spheroidization rate is 88%; grade 3 of spheroidization; graphite size: reaching grade 5; the casting method comprises the following steps of carrying out casting defects with tensile strength of 475.3Mpa, yield strength of 332.7Mpa, elongation of 10.8%, brinell hardness of 181HB, no visible naked eye on the surface to influence use, cleaning the surface of an inner cavity, no phenomena such as residual sand, bonded sand, flash and burr and corrosion resistance degree, carrying out a neutral salt spray test (NSS test) specified in GB/T10125-2012, and having mass loss of 101.3g/m 2 。
Note: carrying out metallographic examination on GB/T9441-2009 nodular cast iron; GB/T10125-2012 artificial atmosphere corrosion test salt spray test; GGB/T228.1-2010 Metal Material tensile test part 1: room temperature test method; brinell hardness test of GB/T231.1-2009 Metal Material part 1: a test method; GB/T1348-2009 nodular iron casting.
Claims (4)
1. The casting method of the high-density high-pressure-resistant nodular valve body is characterized by comprising the following steps:
step one, core making: conveying the coated sand into a core shooting machine die, heating the die to 230-250 ℃, controlling the sand shooting pressure to 0.15-0.4 MPa, controlling the sand shooting time to 3-10s and the crust-forming time to 10-30s to obtain the required sand core; second step, (1) iron melting and casting: manually putting pig iron into a furnace body of a medium-frequency electric furnace, and melting molten iron in the medium-frequency electric furnace for 45 minutes; (2) spheroidizing: spheroidizing by adopting a pit flushing method, wherein before spheroidizing, a nodulizer, an inoculant and the like are filled into a spheroidizing bag, the spheroidizing bag with the height-diameter ratio of 2: 1 is adopted, the nodulizer is added into the bag according to the proportion of 1.8 percent and the inoculant with the size of 10-20mm is 0.9 percent, the nodulizer is added into the bag, then the inoculant is added, finally, dry scrap iron is covered on the nodulizer, surface floating slag is removed, molten iron is heated to 1480-1500 ℃ in a furnace for tapping, molten iron on one side close to an electric furnace on a casting side is flushed into the other side of the spheroidizing bag at one time, 2/3 or 3/4 of the total amount of the spheroidizing bag is injected at one time, and the spheroidizing time is controlled to be 90300s; and (3) casting: the ladle is transported to a casting line through a crown block, the ladle is cast in a manual casting mode, and the casting is finished within 10 to 20min, and the ladle comprises the following chemical components: 3.6 to 3.7 percent of C, 2.2 to 2.4 percent of Si, 0.2 to 0.3 percent of MnS, less than or equal to 0.02 percent of S and less than 0.05 percent of P; (4) turning over the box and shakeout: after casting, the box body is conveyed to a shakeout position along with a conveyor belt, the casting is taken out by manually turning the box body, and a sand core is picked up; thirdly, shot blasting and polishing: and (3) after the casting is picked up, removing oxide skin and sand on the surface of the casting by using a shot blasting machine, and after shot blasting, polishing the surface of the casting by using a grinding wheel machine to ensure that the surface is smooth and flat, thus obtaining the casting.
2. The casting method of the high-density high-pressure-resistant nodular valve body according to claim 1, wherein the nodulizer is a rare earth silicon-iron-magnesium alloy nodulizer, and comprises the following specific components of 6-8% of Ce, 7.0-8.0% of Mg7, 35-40% of Si, 2-3.5% of Ca, less than or equal to 0.5% of Ti, less than or equal to 0.5% of Al, and the balance of Fe.
3. The casting method of the high-density high-pressure-resistant nodular valve body according to claim 1, wherein the inoculant is FeSi75.
4. The casting method of the high-density high-pressure-resistant nodular valve body according to claim 1, wherein the precoated sand is a uniform mixture of 100% by mass of natural water-scrubbed silica sand, 1.0-3.0% by mass of 2124 type phenolic resin, 0.5-0.7% by mass of urotropine solution with the mass fraction of 50% and 0.005-0.01% by mass of olan.
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| CN117960999A (en) * | 2024-04-01 | 2024-05-03 | 安徽省庐江县盛林机械有限公司 | Nodular cast iron pump body for fire control and preparation method thereof |
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