CN117102433A - Semi-closed cavity forming method for medium-large thick-wall steel castings - Google Patents
Semi-closed cavity forming method for medium-large thick-wall steel castings Download PDFInfo
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- CN117102433A CN117102433A CN202311067773.7A CN202311067773A CN117102433A CN 117102433 A CN117102433 A CN 117102433A CN 202311067773 A CN202311067773 A CN 202311067773A CN 117102433 A CN117102433 A CN 117102433A
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- Prior art keywords
- sand
- core
- molding
- casting
- semi
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- Pending
Links
- 238000005266 casting Methods 0.000 title claims abstract description 63
- 238000000034 method Methods 0.000 title claims abstract description 30
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 23
- 239000010959 steel Substances 0.000 title claims abstract description 23
- 239000003110 molding sand Substances 0.000 claims abstract description 52
- 239000004576 sand Substances 0.000 claims abstract description 48
- 238000004519 manufacturing process Methods 0.000 claims abstract description 20
- 238000000465 moulding Methods 0.000 claims abstract description 16
- 239000011230 binding agent Substances 0.000 claims abstract description 12
- -1 phenolic aldehyde Chemical class 0.000 claims abstract description 9
- 230000008569 process Effects 0.000 claims abstract description 9
- 238000004804 winding Methods 0.000 claims abstract description 8
- 238000004140 cleaning Methods 0.000 claims abstract description 7
- 239000000853 adhesive Substances 0.000 claims abstract description 5
- 230000001070 adhesive effect Effects 0.000 claims abstract description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 14
- 239000002184 metal Substances 0.000 claims description 13
- 229910052751 metal Inorganic materials 0.000 claims description 13
- 238000009423 ventilation Methods 0.000 claims description 8
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 7
- 239000001569 carbon dioxide Substances 0.000 claims description 7
- 238000007711 solidification Methods 0.000 claims description 5
- 230000008023 solidification Effects 0.000 claims description 5
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 3
- 229910001018 Cast iron Inorganic materials 0.000 claims description 3
- 239000000463 material Substances 0.000 claims description 3
- 238000003860 storage Methods 0.000 claims description 3
- 238000003466 welding Methods 0.000 claims description 3
- 238000007599 discharging Methods 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims description 2
- 230000003670 easy-to-clean Effects 0.000 abstract description 3
- 230000000694 effects Effects 0.000 abstract description 3
- 230000035699 permeability Effects 0.000 abstract description 3
- 239000002699 waste material Substances 0.000 abstract description 3
- 239000011324 bead Substances 0.000 abstract description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 64
- 238000007528 sand casting Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 239000004115 Sodium Silicate Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 230000005465 channeling Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000012778 molding material Substances 0.000 description 1
- 229910021652 non-ferrous alloy Inorganic materials 0.000 description 1
- 235000019353 potassium silicate Nutrition 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 229910052911 sodium silicate Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- 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
- B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
- B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
- B22C1/20—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents
- B22C1/22—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents of resins or rosins
- B22C1/2233—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents of resins or rosins obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
- B22C1/2246—Condensation polymers of aldehydes and ketones
- B22C1/2253—Condensation polymers of aldehydes and ketones with phenols
-
- 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
Abstract
A semi-closed cavity forming method of a medium-large thick-wall steel casting comprises the steps of firstly, manufacturing a model and a core box; step two, preparing molding sand; step three, adding an adhesive; step four, manufacturing a sand core; step five, casting in a combined mode; step six, demolding and shakeout; step seven, cleaning and checking; the invention adopts the alkaline phenolic aldehyde organic binder, the organic binder burns after casting, the collapsibility of molding sand is effectively improved, the waste sand is very easy to clean, the sand removal difficulty is reduced, the molding difficulty of manufacturing a small molding sand core is reduced by compacting the molding sand core firstly and then solidifying the molding sand core in the operation process, the strength of the molding sand core is improved, meanwhile, the application of the bead sand and the winding of a breathable belt of the core rod of the small molding sand core ensure the air permeability of the molding sand core with a similar shell-core structure, the generation of air holes is prevented, and in addition, according to the shape and the size of a semi-closed cavity and the size of the small cavity, the molding sand with different proportions is adopted, so that the molding requirement of a special-shaped curved surface is met, and the cleaning effect and the surface quality are ensured.
Description
Technical Field
The invention relates to the technical field of sand casting, in particular to a semi-closed cavity forming method for a medium-large thick-wall steel casting.
Background
Sand casting refers to a casting process that produces castings in sand molds. Steel, iron and most nonferrous alloy castings are obtained by sand casting methods. Because the molding materials used for sand casting are cheap and easy to obtain, the casting mold is simple and convenient to manufacture, and is suitable for single-piece production, batch production and mass production of castings, the technology is a basic technology in casting production for a long time, and the sodium silicate sand technology is widely applied to semi-closed (only one end of a cavity for sand production) or small-specification cavities due to low cost, and the thickness of the casting wall of a structure around the cavity is more than 60 mm.
The prior art has the following defects: firstly, adopting ordinary water glass or modified water glass as a binder, adopting a molding sand process of ordinary silica sand as molding sand, wherein after casting, the molding sand has high-temperature residual strength and poor collapsibility, so that the surface of the casting is seriously stuck with sand, the surface of the casting is difficult to clean, and when casting is cast, the existing process causes phenomena of wrapping the molding sand in a cavity by molten steel, chemical sticking and the like under the action of high-temperature metal hydraulic pressure and heat around a semi-closed or small-specification cavity sand core, the cavity is blocked by the sintered molding sand, and the surface of the cavity is damaged after the sintered molding sand cannot be cleaned or cleaned by using tools such as a gouging gun, a grinding wheel and the like, and the small-cavity molding sand is difficult to repair due to the sintering blocking of the small-cavity molding sand, so that the casting is damaged or even scrapped; secondly, the molding difficulty of the special-shaped curved small-sized sand core in the large-sized thick-wall casting in the existing casting process is high, the strength is difficult to ensure, the air permeability of the sand core is poor, and air holes are easy to generate; thirdly, the semi-closed small cavity of the medium-large thick-wall steel casting can not ensure the forming problem of the quality requirement.
Disclosure of Invention
The invention aims to provide a semi-closed cavity forming method in a medium-large thick-wall steel casting, which aims to solve the problems in the prior art.
In order to achieve the above purpose, the present invention provides the following technical solutions: a semi-closed cavity forming method of a medium-large thick-wall steel casting comprises the steps of firstly, manufacturing a model and a core box; step two, preparing molding sand; step three, adding an adhesive; step four, manufacturing a sand core; step five, casting in a combined mode; step six, demolding and shakeout; step seven, cleaning and checking;
in the first step, manufacturing a pattern and a core box according to a casting drawing;
in the second step, molding sand meeting the performance requirements is prepared;
wherein in the third step, an alkaline phenolic aldehyde organic binder is added;
in the fourth step, modeling and core making are carried out by using the model and the core box;
in the fifth step, metal is smelted after the metal is combined and casting is carried out;
in the sixth step, after the molten metal is solidified, breaking up core sand, and taking out the casting;
in the seventh step, the molding sand adhered to the surface of the casting and the cavity is further cleaned, and the structural size of the casting is inspected according to technical requirements and then put in storage.
Preferably, in the first step, a certain shrinkage allowance is reserved when the pattern is manufactured according to the size and the molding requirement of the casting, so that the cavity inside the casting is avoided in the solidification and shrinkage process of the molten metal.
Preferably, in the second step, the foundry sand is prepared by adopting the baozzle sand and the chromite sand as molding sand, and the molding sand are put into a sand mixer according to different proportions to be mixed for 3-5 minutes.
Preferably, the main component of the Baozhu sand is Al 2 O 3 And Al is 2 O 3 The composition is more than 60%, the proportion of the two molding sand is adjusted according to the wall thickness of the casting, when the minimum section size of the casting with the wall thickness being more than 80mm and the sand core is less than 30mm, the mixing proportion of the baozzle sand and the chromite sand is 2:7, the proportion of the baozzle sand is increased along with the increase of the minimum section size of the sand core, and the baozzle sand is fully adopted after the minimum section size of the sand core exceeds 150 mm.
Preferably, in the third step, an alkaline phenolic aldehyde organic binder accounting for 2.5 to 4 percent of the weight of the molding sand is added into the sand mixer, and the molding sand is produced after uniform mixing for 10 to 20 seconds.
Preferably, in the fourth step, the mixed molding sand is filled into a core box for tamping, carbon dioxide is blown in for solidification, carbon dioxide is blown in until the hardness of the sand core reaches 4 inch steel nails which are inserted into the core box for 1/4 length and the core bars with proper sizes are selected according to the size of the sand core, and the molding sand can be made of tubular cast iron materials or steel for welding, so that the strength requirement and the toughness deformation are met.
Preferably, the ventilation belt with proper size is selected on the core bar for winding, and the ventilation belt after winding keeps at least more than 5mm from the surface of the sand core.
Compared with the prior art, the invention has the beneficial effects that: the invention adopts the alkaline phenolic aldehyde organic binder, the organic binder burns after casting, the collapsibility of molding sand is effectively improved, the waste sand is very easy to clean, the sand removal difficulty is reduced, the molding difficulty of manufacturing a small molding sand core is reduced by compacting the molding sand core firstly and then solidifying the molding sand core in the operation process, the strength of the molding sand core is improved, meanwhile, the application of the bead sand and the winding of a breathable belt of the core rod of the small molding sand core ensure the air permeability of the molding sand core with a similar shell-core structure, the generation of air holes is prevented, and in addition, according to the shape and the size of a semi-closed cavity and the size of the small cavity, the molding sand with different proportions is adopted, so that the molding requirement of a special-shaped curved surface is met, and the cleaning effect and the surface quality are ensured.
Drawings
FIG. 1 is a flow chart of the method of the present invention.
Detailed Description
The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments, and all other embodiments obtained by those skilled in the art without making creative efforts based on the embodiments of the present invention are included in the protection scope of the present invention.
Referring to fig. 1, an embodiment of the present invention is provided: a semi-closed cavity forming method of a medium-large thick-wall steel casting comprises the steps of firstly, manufacturing a model and a core box; step two, preparing molding sand; step three, adding an adhesive; step four, manufacturing a sand core; step five, casting in a combined mode; step six, demolding and shakeout; step seven, cleaning and checking;
in the first step, manufacturing a pattern and a core box according to a casting drawing, and keeping a certain shrinkage allowance according to the casting size and the molding requirement when manufacturing the pattern so as to avoid generating a cavity in the casting in the solidification shrinkage process of molten metal;
in the second step, molding sand meeting the performance requirement is prepared, the foundry sand is prepared by adopting the baozu sand and chromite sand as the molding sand, and the molding sand is filled into a sand mixer according to different proportions to be mixed for 3-5 minutes, wherein the main component of the baozu sand is Al 2 O 3 And Al is 2 O 3 The component is more than 60%, the proportion of two kinds of molding sand is adjusted according to the wall thickness of the casting, when the minimum section size of the casting with the wall thickness being more than 80mm and the sand core is less than 30mm, the mixing proportion of the baozzle sand and the chromite sand is 2:7, the proportion of the baozzle sand is increased along with the increase of the minimum section size of the sand core, and the baozzle sand is adopted after the minimum section size of the sand core exceeds 150 mm;
in the third step, adding an alkali phenolic aldehyde organic binder, adding the alkali phenolic aldehyde organic binder accounting for 2.5-4% of the weight of the molding sand into a sand mixer, uniformly mixing for 10-20 seconds, and discharging sand;
in the fourth step, the mould and the core box are utilized to mould and core, the mixed molding sand is filled into the core box to be tamped, carbon dioxide is blown in to solidify, carbon dioxide is blown in until the hardness of the sand core reaches 4 inch steel nails which are inserted into the core box for 1/4 length and are difficult to enter, a core bar with proper size is selected according to the size of the sand core, a tubular cast iron material can be adopted, steel welding can also be adopted, the strength requirement and the toughness deformation are met, a ventilation belt with proper size is selected on the core bar to be wound, and the distance between the ventilation belt after winding and the surface of the sand core is at least 5 mm;
in the fifth step, metal is smelted after the metal is combined and casting is carried out;
in the sixth step, after the molten metal is solidified, breaking up core sand, and taking out the casting;
in the seventh step, the molding sand adhered to the surface of the casting and the cavity is further cleaned, and the structural size of the casting is inspected according to technical requirements and then put in storage.
Based on the above, the invention has the advantages that: according to the invention, the alkaline phenolic aldehyde organic binder is adopted, the organic binder burns after casting, so that the collapsibility of molding sand is effectively improved, waste sand is very easy to clean, the sand removal difficulty is reduced, a novel curing process of carbon dioxide hardening is adopted, the operation is convenient and fast, the efficiency is improved, the cost is reduced, the sand core is compacted and then cured in the operation process, the molding difficulty for manufacturing small-sized sand cores is reduced, the strength of the sand cores is improved, the molding requirements of special-shaped curved surfaces are met according to the shape and size of a semi-closed cavity and the size of a small cavity, the cleaning effect and the surface quality are ensured, the application of the foundry sand and the winding ventilation belt of the core bars of the small-sized sand cores are ensured, the ventilation property of the sand cores similar to the shell channeling core structure is ensured, and the generation of air holes is prevented.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention 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 invention 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 reference sign in a claim should not be construed as limiting the claim concerned.
Claims (7)
1. A semi-closed cavity forming method of a medium-large thick-wall steel casting comprises the steps of firstly, manufacturing a model and a core box; step two, preparing molding sand; step three, adding an adhesive; step four, manufacturing a sand core; step five, casting in a combined mode; step six, demolding and shakeout; step seven, cleaning and checking; the method is characterized in that:
in the first step, manufacturing a pattern and a core box according to a casting drawing;
in the second step, molding sand meeting the performance requirements is prepared;
wherein in the third step, an alkaline phenolic aldehyde organic binder is added;
in the fourth step, modeling and core making are carried out by using the model and the core box;
in the fifth step, metal is smelted after the metal is combined and casting is carried out;
in the sixth step, after the molten metal is solidified, breaking up core sand, and taking out the casting;
in the seventh step, the molding sand adhered to the surface of the casting and the cavity is further cleaned, and the structural size of the casting is inspected according to technical requirements and then put in storage.
2. The method for molding a semi-closed cavity of a medium-and-large-sized thick-wall steel casting according to claim 1, wherein the method comprises the following steps: in the first step, a certain shrinkage allowance is reserved when a model is manufactured according to the size and the molding requirement of the casting, so that the generation of cavities in the casting in the solidification shrinkage process of molten metal is avoided.
3. The method for molding a semi-closed cavity of a medium-and-large-sized thick-wall steel casting according to claim 1, wherein the method comprises the following steps: in the second step, the Baozhu sand and chromite sand are adopted as molding sand, and the molding sand are put into a sand mixer according to different proportions to be mixed for 3-5 minutes.
4. A method for molding a semi-closed cavity for a medium-and large-sized thick-wall steel casting according to claim 3, wherein: the main component of the Baozhu sand is Al 2 O 3 And Al is 2 O 3 The composition is more than 60%, the proportion of the two molding sand is adjusted according to the wall thickness of the casting, when the minimum section size of the casting with the wall thickness being more than 80mm and the sand core is less than 30mm, the mixing proportion of the baozzle sand and the chromite sand is 2:7, the proportion of the baozzle sand is increased along with the increase of the minimum section size of the sand core, and the baozzle sand is fully adopted after the minimum section size of the sand core exceeds 150 mm.
5. The method for molding a semi-closed cavity of a medium-and-large-sized thick-wall steel casting according to claim 1, wherein the method comprises the following steps: in the third step, adding alkaline phenolic aldehyde organic adhesive accounting for 2.5-4% of the weight of the molding sand into a sand mixer, uniformly mixing for 10-20 seconds, and discharging sand.
6. The method for molding a semi-closed cavity of a medium-and-large-sized thick-wall steel casting according to claim 1, wherein the method comprises the following steps: in the fourth step, the mixed molding sand is filled into a core box for tamping, carbon dioxide is blown in for solidification, carbon dioxide is blown in until the hardness of the sand core reaches 1/4 inch of the length of the steel nail, the sand core is difficult to enter, and a core bar with a proper size is selected according to the size of the sand core, so that a tubular cast iron material can be adopted, steel welding can be adopted, and the strength requirement and the toughness deformation are met.
7. The method for molding the semi-closed cavity of the medium-large thick-wall steel casting, which is characterized by comprising the following steps of: and selecting a ventilation belt with a proper size on the core bar for winding, wherein the distance between the ventilation belt after winding and the surface of the sand core is at least 5 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311067773.7A CN117102433A (en) | 2023-08-23 | 2023-08-23 | Semi-closed cavity forming method for medium-large thick-wall steel castings |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311067773.7A CN117102433A (en) | 2023-08-23 | 2023-08-23 | Semi-closed cavity forming method for medium-large thick-wall steel castings |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117102433A true CN117102433A (en) | 2023-11-24 |
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ID=88808626
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311067773.7A Pending CN117102433A (en) | 2023-08-23 | 2023-08-23 | Semi-closed cavity forming method for medium-large thick-wall steel castings |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117102433A (en) |
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2023
- 2023-08-23 CN CN202311067773.7A patent/CN117102433A/en active Pending
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