CN112475219B - Method for manufacturing large shell mold shell core by using high-fluidity high-melting-point precoated sand - Google Patents
Method for manufacturing large shell mold shell core by using high-fluidity high-melting-point precoated sand Download PDFInfo
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- CN112475219B CN112475219B CN202011126698.3A CN202011126698A CN112475219B CN 112475219 B CN112475219 B CN 112475219B CN 202011126698 A CN202011126698 A CN 202011126698A CN 112475219 B CN112475219 B CN 112475219B
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- sand
- precoated sand
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- mold
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- 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
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- 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
- B22C1/02—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives
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- 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
- B22C1/02—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives
- B22C1/14—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives for separating the pattern from the mould
-
- 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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C5/00—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose
- B22C5/04—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose by grinding, blending, mixing, kneading, or stirring
- B22C5/0409—Blending, mixing, kneading or stirring; Methods therefor
Abstract
The invention relates to a method for manufacturing a large shell mold core by using high-fluidity high-melting-point precoated sand, which comprises the following manufacturing steps: preparing precoated sand, heating the raw sand to a specified temperature, quantitatively adding the heated raw sand into a sand mixer, then quantitatively adding phenolic resin serving as a binder, stirring and mixing the raw sand and the phenolic resin by the sand mixer, adding a hardening agent into the fully mixed raw sand and the phenolic resin, then adding a lubricant, cooling and screening, and then mixing the screened substances with a modified additive containing sodium chloride and magnesium chloride to prepare the precoated sand; manufacturing a shell mold core, manufacturing a mold of the shell mold core, heating the mold to 200-320 ℃, shooting the precoated sand into the mold by a shell mold or a core shooting machine in a multi-azimuth multi-sand shooting head sand shooting mode, filling the precoated sand into the mold, softening the precoated sand after the precoated sand contacts the high temperature of the mold, and forming after cooling.
Description
Technical Field
The invention relates to the technical field of shell mold and shell core casting, in particular to a method for manufacturing a large-scale shell mold shell core by using high-fluidity high-melting-point precoated sand.
Background
The shell mold casting is a process of covering a heated metal template with molding sand (phenolic resin coated sand) which is hardened to form a thin shell, and then heating and curing the thin shell to achieve sufficient strength and rigidity, wherein the casting process of the shell core is similar to that of the shell mold. With the development of shell mold and shell core casting technology, the shell mold technology is more and more widely applied, but at the current technical level, large-sized shell molds and shell cores (the weight of the shell molds and the shell cores is more than 50KG or the external dimension of the shell molds and the shell cores is more than 800mm multiplied by 500mm multiplied by 300 mm) are difficult to manufacture, one of the key points of the shell mold (core) casting technology is precoated sand, the higher the softening point of phenolic resin of the precoated sand is, and the longer the sand shooting time is, the larger the cast shell molds (cores) are. However, the large casting is difficult to realize by using the phenolic resin precoated sand at present, so a new method for manufacturing the large shell type shell core is provided.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method for manufacturing a large-scale shell core by using high-fluidity high-melting-point precoated sand, which can fill the precoated sand into a mold cavity to the maximum extent and can manufacture a high-quality shell and a shell core with large weight, large external dimension and complex shape.
The technical purpose of the invention is realized by the following technical scheme:
a method for manufacturing a large-scale shell-type shell core by using high-fluidity high-melting-point precoated sand comprises the following steps of manufacturing the precoated sand and the shell-type shell core,
preparing precoated sand, heating the raw sand to a specified temperature, quantitatively adding the heated raw sand into a sand mixer, then quantitatively adding phenolic resin serving as a binder, stirring and mixing the raw sand and the phenolic resin by the sand mixer, contacting the phenolic resin with the high-temperature raw sand, immediately melting and adhering to the surface of the raw sand, adding a hardening agent into the fully mixed raw sand and phenolic resin, enabling the phenolic resin adhered to sand grains to be subjected to chemical reaction after encountering the hardening agent and then to be hardened into sand clusters, adding a modified additive containing sodium chloride and magnesium chloride within 3-5 seconds, then adding a lubricant, scattering the sand clusters after the lubricant, keeping the phenolic resin on the surface of the sand grains to the maximum extent in the process of scattering the clustered precoated sand, and screening after cooling to prepare the precoated sand;
manufacturing a shell mold core, manufacturing a mold of the shell mold core, heating the mold to 200-320 ℃, shooting the precoated sand into the mold by a shell mold or a core shooting machine in a multi-azimuth multi-sand shooting head sand shooting mode, filling the precoated sand into the mold, softening the precoated sand after the precoated sand contacts the high temperature of the mold, and forming after cooling.
In one embodiment, the concentration of the modifying additive is 10% -15% of a mixed aqueous solution of sodium chloride and magnesium chloride, wherein the sodium chloride accounts for 20% -30% and the magnesium chloride accounts for 70% -80% of the sodium chloride and the magnesium chloride by mass fraction, and the adding amount of the modifying additive accounts for 0.15% -0.2% of the mass of the phenolic resin in the precoated sand.
In one embodiment, the preparation method of the modified additive comprises the steps of adding salt and industrial magnesium chloride into a container according to a certain proportion, adding purified water into the container, mechanically stirring, standing for 24 hours, transferring the solution after standing into a distillation still, distilling to obtain sodium chloride and magnesium chloride crystals, wherein the sodium chloride accounts for 20% -30% and the magnesium chloride accounts for 70% -80% by mass fraction, cooling, and performing vacuum seal storage, wherein when the modified additive is used as the modified additive, the sodium chloride and the magnesium chloride crystals are prepared into 10% -15% sodium chloride and magnesium chloride aqueous solutions.
In one embodiment, purified water is injected at a solute concentration of 30%, wherein the solutes are 20% -30% sodium chloride and 70% -80% magnesium chloride.
In one embodiment, the raw sand is heated to 110-.
In one embodiment, the addition amount of the phenolic resin is 2.0-2.6% of the total weight of the raw sand.
In one embodiment, the hardener is added in an amount of 0.5% by weight of the phenolic resin.
In one embodiment, the lubricant is added in an amount of 0.5% to 1.0% by weight of the phenolic resin, and the lubricant is added in an amount proportional to the weight of the phenolic resin.
In one embodiment, when the lubricant is added in the process of manufacturing the precoated sand, the accumulation angle of the precoated sand is less than or equal to 20.5 degrees, which is beneficial to improving the flowability of the precoated sand.
In one embodiment, the hardener is urotropin during the production of the precoated sand.
The invention has the following beneficial effects:
the precoated sand is modified by using aqueous solutions of sodium chloride and magnesium chloride, the softening point of phenolic resin is increased to 105 ℃, and the sand shooting time can be greatly prolonged when the precoated sand is used for manufacturing shells and cores, so that the flowability of the precoated sand is good in the process of manufacturing shell cores of shells, the softening time is prolonged, the precoated sand can fully fill a mold, and high-quality shells and cores with large weight, large appearance size and complex shapes can be manufactured;
the invention adopts the method of multi-azimuth multi-sand shooting head simultaneous sand shooting to manufacture the shell mould and the shell core, when the total sand storage amount of the shell mould or the core shooting machine sand shooting head is ensured to be more than 2 times of the weight of the manufactured shell mould and the manufactured shell core, the precoated sand with high fluidity and softening point is selected, the sufficient supply of the precoated sand can be ensured when the shell mould and the shell core are manufactured, and the sand shooting time when the shell mould and the shell core are manufactured is relatively prolonged.
Detailed Description
The present invention will now be described in detail with reference to examples.
A method for manufacturing a large-scale shell-type shell core by using high-fluidity high-melting-point precoated sand comprises the following steps of manufacturing the precoated sand and manufacturing the shell-type shell core.
Preparing precoated sand, heating the raw sand to 110-150 ℃, quantitatively adding the heated raw sand into a sand mixer, then quantitatively adding phenolic resin serving as a binder, wherein the addition amount of the phenolic resin is 2.0-2.6% of the total weight of the raw sand, stirring and mixing the raw sand and the phenolic resin by the sand mixer, contacting the phenolic resin with the high-temperature raw sand to melt and adhere to the surface of the raw sand, adding a hardening agent into the fully mixed raw sand and the phenolic resin, wherein the addition amount of the hardening agent is 0.5% of the weight of the phenolic resin, enabling the phenolic resin adhered to sand grains to be subjected to chemical reaction after encountering the hardening agent and then to be immediately hardened into sand lumps, then adding a modified additive comprising sodium chloride and magnesium chloride within 3-5 seconds, increasing the softening point of the phenolic resin to 105 ℃, then adding a lubricant, wherein the addition amount of the lubricant is 0.5-1.0% of the weight of the phenolic resin, the addition amount of the lubricant is in direct proportion to the weight of the phenolic resin, the sand cluster is broken up after the lubricant, the phenolic resin on the surface of the sand is retained to the maximum extent in the process of breaking up the conglomerated precoated sand, and the precoated sand is prepared by screening after cooling.
The method comprises the steps of manufacturing a shell mold core, manufacturing a mold of the shell mold core, heating the mold to a temperature of 200-320 ℃, injecting precoated sand into the mold by a shell molding machine or a core shooting machine in a multi-direction multi-sand-shooting-head sand shooting mode, filling the precoated sand into the mold, softening the precoated sand after the precoated sand contacts the high temperature of the mold, cooling and molding, softening the precoated sand immediately when the precoated sand meets the high temperature, wherein different precoated sand adhesives have different softening points, namely the precoated sand starts to soften when meeting an environment of 85-98 ℃, greatly reduces the fluidity after the precoated sand softens, and indicates that the sand shooting process reaches the end point when the shell mold and the shell core are manufactured, and the continuous length of the sand shooting process are in direct proportion to the sizes of the shell mold and the shell core which can be manufactured.
In this embodiment, the concentration of the modifying additive is 10% to 15% of the mixed aqueous solution of sodium chloride and magnesium chloride, wherein the sodium chloride is 20% to 30% and the magnesium chloride is 70% to 80% of the mixed aqueous solution of sodium chloride and magnesium chloride by mass fraction.
In the embodiment, the preparation method of the modified additive comprises the steps of adding salt and industrial magnesium chloride into a container according to a proportion, injecting purified water into the container according to a solute concentration of 30%, mechanically stirring, standing for 24 hours, transferring the solution after standing into a distillation still for distillation to prepare sodium chloride and magnesium chloride crystals, wherein the sodium chloride is 20% -30% and the magnesium chloride is 70% -80%, cooling, independently vacuum-sealing and packaging every 50g of the solution, directly configuring the sodium chloride and the magnesium chloride crystals into 10% -15% sodium chloride and magnesium chloride aqueous solutions on site when the modified additive is used as the modified additive, and using the sodium chloride and the magnesium chloride aqueous solutions to improve the softening point of the precoated sand made of the alkaline phenolic resin.
In the embodiment, when the lubricant is added in the process of manufacturing the coated sand, the stacking angle of the coated sand is less than or equal to 20.5 degrees, which is beneficial to improving the fluidity of the coated sand.
In this example, the hardener was urotropin during the production of the precoated sand.
The precoated sand is modified by using aqueous solutions of sodium chloride and magnesium chloride, the softening point of phenolic resin is increased to 105 ℃, and the sand shooting time can be greatly prolonged when the precoated sand is used for manufacturing shells and cores, so that the flowability of the precoated sand is good in the process of manufacturing shell cores of shells, the softening time is prolonged, the precoated sand can fully fill a mold, and high-quality shells and cores with large weight, large appearance size and complex shapes can be manufactured;
the invention adopts the method of multi-azimuth multi-sand shooting head simultaneous sand shooting to manufacture the shell mould and the shell core, when the total sand storage amount of the shell mould or the core shooting machine sand shooting head is ensured to be more than 2 times of the weight of the manufactured shell mould and the manufactured shell core, the precoated sand with high fluidity and softening point is selected, the sufficient supply of the precoated sand can be ensured when the shell mould and the shell core are manufactured, and the sand shooting time when the shell mould and the shell core are manufactured is relatively prolonged.
According to the mass percentage, the addition amount of the modified additive (20-30% of sodium chloride and 70-80% of magnesium chloride crystals) accounts for 0.15-0.2% of the phenolic resin in the precoated sand, the softening point of the precoated sand can be improved by 8-10%, but the addition amount of the modified additive cannot be too high, and the plasticity of the prepared shell-type shell core can be reduced if the modified additive is excessively added, and the specific data are shown in the following table 1.
TABLE 1
| Additive addition amount (%) | Precoated sand softening point (. degree. C.) |
| Is free of | 105 |
| 0.15 | 113.6 |
| 0.18 | 114.2 |
| 0.2 | 115.8 |
The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.
Claims (9)
1. A method for manufacturing a large shell mold core by using high-fluidity high-melting-point precoated sand is characterized by comprising the following steps of manufacturing the precoated sand and the shell mold core,
preparing precoated sand, heating the raw sand to a specified temperature, quantitatively adding the heated raw sand into a sand mixer, then quantitatively adding phenolic resin serving as a binder, stirring and mixing the raw sand and the phenolic resin by the sand mixer, adding a hardening agent into the fully mixed raw sand and the phenolic resin, then adding a modified additive of which the components are sodium chloride and magnesium chloride, then adding a lubricant, cooling and screening to prepare the precoated sand;
manufacturing a shell mold core, manufacturing a mold of the shell mold core, heating the mold to 200-320 ℃, shooting the precoated sand into the mold by a shell molding machine or a core shooting machine in a multi-azimuth multi-sand shooting head sand shooting mode, filling the precoated sand into the mold, softening the precoated sand after contacting the high temperature of the mold, and forming after cooling;
The modified additive is a mixed aqueous solution of 10-15% of sodium chloride and magnesium chloride, wherein the sodium chloride accounts for 20-30% and the magnesium chloride accounts for 70-80% of the sodium chloride and the magnesium chloride by mass fraction, and the addition amount of the modified additive accounts for 0.15-0.2% of the mass of the phenolic resin in the precoated sand.
2. The method for manufacturing a large-scale shell core using high-fluidity high-melting-point precoated sand according to claim 1, wherein the modifying additive is prepared by adding salt and industrial magnesium chloride in a ratio into a vessel, adding purified water into the vessel, mechanically stirring, standing for 24 hours, transferring the solution after standing to a distillation still for distillation to obtain sodium chloride and magnesium chloride crystals, wherein the sodium chloride and the magnesium chloride are 20 to 30% and 70 to 80% by mass, cooling, and storing in a vacuum seal manner, and when the modifying additive is used, the sodium chloride and the magnesium chloride crystals are prepared into 10 to 15% aqueous solution of the sodium chloride and the magnesium chloride.
3. The method of claim 2, wherein the injection of purified water is performed at a solute concentration of 30%, wherein the solutes are 20% -30% sodium chloride and 70% -80% magnesium chloride.
4. The method for manufacturing a large shell mold core by using high-fluidity and high-melting-point precoated sand as claimed in claim 1, wherein the raw sand is heated to 110-150 ℃.
5. The method of making large shell cores from high flow, high melting point coated sand according to claim 1, wherein the phenolic resin is added in an amount of 2.0 to 2.6% of the total weight of the raw sand.
6. The method of making large shell cores from high flow, high melting point coated sand according to claim 5, wherein the amount of hardener added is 0.5% by weight of the phenolic resin.
7. The method of making large shell cores from high flow, high melting point coated sand according to claim 5, wherein the lubricant is added in an amount of 0.5% to 1.0% by weight of the phenolic resin.
8. The method of making a large shell core of a shell mold using high flow, high melting point precoated sand according to claim 1, wherein the angle of accumulation of the precoated sand is less than or equal to 20.5 ° when the lubricant is added during the preparation of the precoated sand.
9. The method for manufacturing large shell mold cores using high fluidity, high melting point precoated sand according to any one of claims 1 to 8, wherein the hardening agent is urotropin.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011126698.3A CN112475219B (en) | 2020-10-20 | 2020-10-20 | Method for manufacturing large shell mold shell core by using high-fluidity high-melting-point precoated sand |
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| CN202011126698.3A CN112475219B (en) | 2020-10-20 | 2020-10-20 | Method for manufacturing large shell mold shell core by using high-fluidity high-melting-point precoated sand |
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| CN112475219B true CN112475219B (en) | 2022-07-29 |
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| CA2134156A1 (en) * | 1993-11-22 | 1995-05-23 | Thomas P. Klun | Coatable compositions, abrasive articles made therefrom, and methods of making and using same |
| CN103658506B (en) * | 2013-12-31 | 2016-03-30 | 安顺学院 | Easy filling precoated sand and preparation technology thereof |
| CN109226663B (en) * | 2018-11-28 | 2020-12-04 | 韶关市新世科壳型铸造有限公司 | Method for manufacturing large shell mold shell core by using high-fluidity high-melting-point precoated sand |
| CN109928655B (en) * | 2019-04-02 | 2021-12-24 | 交通运输部科学研究院 | Core-shell type anti-icing modifier, manufacturing method thereof and anti-icing coating comprising same |
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