CN108971418B - Preparation method of anti-shelling precoated sand - Google Patents
Preparation method of anti-shelling precoated sand Download PDFInfo
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- CN108971418B CN108971418B CN201810724301.7A CN201810724301A CN108971418B CN 108971418 B CN108971418 B CN 108971418B CN 201810724301 A CN201810724301 A CN 201810724301A CN 108971418 B CN108971418 B CN 108971418B
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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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Abstract
The invention provides a precoated sand additive for preventing sand core from shelling, which comprises 5-8% of a silane coupling agent, 2-5% of benzoic acid, 20-35% of ethylene glycol, 3-6% of ammonium chloride and the balance of water; an anti-shelling precoated sand comprises 2-4% of phenolic resin, 1-2% of urotropine, 0.5-1.5% of an anti-shelling additive, 0.5% of calcium stearate and the balance of raw sand; and a preparation method of the shelling-proof precoated sand. The invention has the beneficial effects that: the precoated sand additive for preventing the sand core from being shelled is added in the precoated sand manufacturing process, so that the curing speed of the precoated sand is obviously improved, meanwhile, the overall strength of the precoated sand is improved by optimizing the component proportion and the manufacturing process parameters of the precoated sand, the uniformity of a shell layer is improved, the sand falling phenomenon of the inner cavity of the sand core when the sand core is overturned to the empty time in the core manufacturing process is effectively improved, and the core manufacturing rejection rate is reduced, so that the production cost is reduced, and the precoated sand additive is suitable for the.
Description
Technical Field
The invention belongs to the technical field of casting industry, and particularly relates to a precoated sand additive for preventing sand cores from being shelled, anti-shelling precoated sand and a preparation method thereof.
Background
The precoated sand is invented by doctor clonning, Germany during the second war, and its technological process is that the powdered thermosetting phenolic resin and raw sand are mechanically mixed, and when heated, they are solidified. Then, the precoated sand is prepared by thermoplastic phenolic resin, a latent curing agent (urotropine) and a lubricant through a certain coating process, when the precoated sand is heated, the resin coated on the surface of the sand is melted, and the melted resin is quickly converted from a linear structure into a non-melted body structure under the action of methylene decomposed from the urotropine, so that the precoated sand is cured and molded.
At present, in the process of casting precoated sand during core making, when the precoated sand is turned to be empty, the inner cavity of the sand core has a sand drop phenomenon, so that the sand core has defects, a large amount of manual repair is needed in the later period, the sand core is scrapped when the sand core is serious, the rejection rate of the core making is increased (the rejection rate can reach 15% -25% when the sand core is serious), raw materials are wasted, the cost is increased, and the.
Disclosure of Invention
The invention aims to provide a precoated sand additive for improving the curing speed of precoated sand and preventing a sand core from shelling, anti-shelling precoated sand and a preparation method thereof.
In order to solve the technical problems, the invention adopts the technical scheme that: a precoated sand additive for preventing sand core from shelling is prepared from the following components in parts by weight: comprises 5-8% of silane coupling agent, 2-5% of benzoic acid, 20-35% of glycol, 3-6% of ammonium chloride and the balance of water.
In the technical scheme, the preferable silane coupling agent is gamma-aminopropyl triethoxysilane.
The unshelling-proof precoated sand containing the unshelling-proof precoated sand additive is prepared from the following components in percentage by weight: 2-4% of phenolic resin, 1-2% of urotropine, 0.5-1.5% of shelling-preventing additive, 0.5% of calcium stearate and the balance of raw sand.
In the technical scheme, preferably, the content of silicon dioxide in the raw sand is more than 90%.
In the technical scheme, preferably, the raw sand comprises 70% of scouring sand with the particle size of 70/140 meshes and 30% of scouring sand with the particle size of 50/100 meshes.
In the technical scheme, the polymerization speed of the phenolic resin is preferably 20-22 seconds.
A preparation method of unshelling-proof precoated sand comprises the following specific preparation steps:
(1) weighing the components in parts by weight, heating the raw sand to the temperature of 130-;
(2) adding phenolic resin when the sand release time reaches 10-15 seconds, and mixing and stirring for 50-60 seconds;
(3) adding an anti-shelling precoated sand additive, mixing and stirring;
(4) when the temperature of the sand is reduced to 110-112 ℃, adding a curing agent urotropine solution, mixing and stirring for 25-35 seconds, adding the curing agent, and simultaneously opening the bottom air blast of the sand mixer and a dehumidification valve at the top end of the sand mixer for drying;
(5) adding lubricant calcium stearate, and mixing and stirring;
(6) when the temperature of the sand is reduced to 67-73 ℃, the sand is taken out, crushed, cooled to below 40 ℃ and packaged to obtain the precoated sand.
In the technical scheme, the time from sand control to sand production is preferably controlled to be between 150 seconds and 160 seconds.
In the technical scheme, preferably, the anti-shelling precoated sand additive is prepared before the step (1): weighing the components according to the dosage, sequentially adding benzoic acid and ammonium chloride into water, stirring and dissolving, and standing for 4-6 hours; mixing a silane coupling agent and glycol, adding the mixture into a benzoic acid and ammonium chloride aqueous solution, uniformly stirring, standing for 2 hours and barreling for later use.
In the technical scheme, the rotation speed of the sand mixer in the preparation process is preferably 65-95 r/min.
The invention has the advantages and positive effects that: the precoated sand additive for preventing the sand core from being shelled is added in the precoated sand manufacturing process, so that the curing speed of the precoated sand is obviously improved, meanwhile, the overall strength of the precoated sand is improved by optimizing the component proportion and the manufacturing process parameters of the precoated sand, the uniformity of a shell layer is improved, the sand falling phenomenon of the inner cavity of the sand core when the sand core is overturned to the empty time in the core manufacturing process is effectively improved, and the core manufacturing rejection rate is reduced, so that the production cost is reduced, and the precoated sand additive is suitable for the.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to specific embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
Preparing unshelling-proof precoated sand: heating 96 parts of raw sand by weight to 130 ℃, putting the raw sand into a sand mixer, controlling the rotating speed of the sand mixer to be 65r/min, and controlling the sand discharge time to be within 20 seconds; when the sand releasing time is 10 seconds, adding 2 parts of phenolic resin, and mixing and stirring for 55 seconds; adding 0.5 part of unshelling-proof precoated sand additive, mixing and stirring; when the temperature of the sand is reduced to 112 ℃, adding 1 part of a curing agent urotropine solution, mixing and stirring for 30 seconds, adding the curing agent, and simultaneously opening the bottom air blast of the sand mixer and a dehumidification valve at the top end of the sand mixer for drying; 0.5 part of lubricant calcium stearate is added, and the mixture is mixed and stirred; when the temperature of the sand is reduced to 69 ℃, the sand is taken out, crushed, cooled to below 40 ℃ and packaged to obtain the precoated sand.
Preparing an anti-shelling precoated sand additive: weighing the components in parts by weight, sequentially adding 3 parts of benzoic acid and 5 parts of ammonium chloride into 57 parts of water, stirring for dissolving, and standing for 4 hours; mixing 5 parts of silane coupling agent and 30 parts of ethylene glycol, adding the mixture into benzoic acid and ammonium chloride aqueous solution, uniformly stirring, standing for 2 hours and barreling for later use.
Example 2
Preparing unshelling-proof precoated sand: taking 94 parts by weight of raw sand, heating to 134 ℃, putting the raw sand into a sand mixer, controlling the rotation speed of the sand mixer to be 95r/min and controlling the sand discharging time to be within 20 seconds; when the sand release time is 12 seconds, adding 3 parts of phenolic resin, and mixing and stirring for 50 seconds; adding 1 part of unshelling-proof precoated sand additive, mixing and stirring; when the temperature of the sand is reduced to 110 ℃, adding 1.5 parts of a curing agent urotropine solution, mixing and stirring for 25 seconds, adding the curing agent, and simultaneously opening the bottom air blast of the sand mixer and a dehumidification valve at the top end of the sand mixer for drying; 0.5 part of lubricant calcium stearate is added, and the mixture is mixed and stirred; when the temperature of the sand is reduced to 67 ℃, the sand is taken out, crushed, cooled to below 40 ℃ and packaged to obtain the precoated sand.
Preparing an anti-shelling precoated sand additive: weighing the components in parts by weight, sequentially adding 2 parts of benzoic acid and 3 parts of ammonium chloride into 70 parts of water, stirring and dissolving, and standing for 4 hours; mixing 5 parts of silane coupling agent and 20 parts of ethylene glycol, adding the mixture into benzoic acid and ammonium chloride aqueous solution, uniformly stirring, standing for 2 hours and barreling for later use.
Example 3
Preparing unshelling-proof precoated sand: taking 95 parts of raw sand by weight, heating to 130 ℃, putting the raw sand into a sand mixer, controlling the rotation speed of the sand mixer to be 70r/min, and controlling the sand discharge time to be within 20 seconds; when the sand releasing time reaches 14 seconds, adding 2.3 parts of phenolic resin, and mixing and stirring for 55 seconds; adding 1.2 parts of unshelling-proof precoated sand additive, mixing and stirring; when the temperature of the sand is reduced to 112 ℃, adding 1 part of a curing agent urotropine solution, mixing and stirring for 25 seconds, adding the curing agent, and simultaneously opening the bottom air blast of the sand mixer and a dehumidification valve at the top end of the sand mixer for drying; 0.5 part of lubricant calcium stearate is added, and the mixture is mixed and stirred; when the temperature of the sand is reduced to 67 ℃, the sand is taken out, crushed, cooled to below 40 ℃ and packaged to obtain the precoated sand.
Preparing an anti-shelling precoated sand additive: weighing the components in parts by weight, sequentially adding 5 parts of benzoic acid and 6 parts of ammonium chloride into 46 parts of water, stirring for dissolving, and standing for 6 hours; mixing 8 parts of silane coupling agent and 35 parts of ethylene glycol, adding the mixture into benzoic acid and ammonium chloride aqueous solution, uniformly stirring, standing for 2 hours and barreling for later use.
Example 4
Preparing unshelling-proof precoated sand: taking 92 parts of raw sand by weight, heating the raw sand to 132 ℃, putting the raw sand into a sand mixer, controlling the rotation speed of the sand mixer to be 80r/min, and controlling the sand discharge time to be within 20 seconds; when the sand release time is 15 seconds, adding 4 parts of phenolic resin, and mixing and stirring for 60 seconds; adding 1.5 parts of unshelling-proof precoated sand additive, mixing and stirring; when the temperature of the sand is reduced to 111 ℃, adding 2 parts of a curing agent urotropine solution, mixing and stirring for 35 seconds, adding the curing agent, and simultaneously opening the bottom air blast of the sand mixer and a dehumidification valve at the top end of the sand mixer for drying; 0.5 part of lubricant calcium stearate is added, and the mixture is mixed and stirred; when the temperature of the sand is reduced to 73 ℃, the sand is taken out, crushed, cooled to below 40 ℃ and packaged to obtain the precoated sand.
Preparing an anti-shelling precoated sand additive: weighing the components in parts by weight, sequentially adding 4 parts of benzoic acid and 4 parts of ammonium chloride into 60 parts of water, stirring for dissolving, and standing for 5 hours; mixing 7 parts of silane coupling agent and 25 parts of ethylene glycol, adding the mixture into benzoic acid and ammonium chloride aqueous solution, uniformly stirring, standing for 2 hours and barreling for later use.
Comparative example
Preparing precoated sand: taking 92 parts of raw sand by weight, heating the raw sand to 132 ℃, putting the raw sand into a sand mixer, controlling the rotation speed of the sand mixer to be 80r/min, and controlling the sand discharge time to be within 20 seconds; when the sand release time is 15 seconds, adding 4 parts of phenolic resin, and mixing and stirring for 60 seconds; when the temperature of the sand is reduced to 111 ℃, adding 2 parts of a curing agent urotropine solution, mixing and stirring for 35 seconds, adding the curing agent, and simultaneously opening the bottom air blast of the sand mixer and a dehumidification valve at the top end of the sand mixer for drying; 0.5 part of lubricant calcium stearate is added, and the mixture is mixed and stirred; when the temperature of the sand is reduced to 73 ℃, the sand is taken out, crushed, cooled to below 40 ℃ and packaged to obtain the precoated sand.
The test data for examples 1-4 and the control are shown in the following table:
as can be seen from the above table, examples 1 to 4 have significantly improved hardening rate and incrustation thickness compared to the comparative example.
The embodiments of the present invention have been described in detail, but the description is only for the preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.
Claims (7)
1. The preparation method of the unshelling-proof precoated sand is characterized by comprising the following specific preparation steps:
(1) weighing the components according to the weight ratio, heating the raw sand to the temperature of 130-;
(2) adding phenolic resin when the sand release time reaches 10-15 seconds, and mixing and stirring for 50-60 seconds;
(3) adding an anti-shelling precoated sand additive, mixing and stirring;
(4) when the temperature of the sand is reduced to 110-112 ℃, adding a curing agent urotropine solution, mixing and stirring for 25-35 seconds, adding the curing agent, and simultaneously opening the bottom air blast of the sand mixer and a dehumidification valve at the top end of the sand mixer for drying;
(5) adding lubricant calcium stearate, and mixing and stirring;
(6) when the temperature of the sand is reduced to 67-73 ℃, discharging the sand, crushing, cooling to below 40 ℃, and packaging to obtain the precoated sand;
wherein the weight ratio of the components is 2-4% of phenolic resin, 1-2% of urotropine, 0.5-1.5% of anti-shelling additive, 0.5% of calcium stearate and the balance of raw sand;
preparing an anti-shelling precoated sand additive before the step (1): sequentially adding benzoic acid and ammonium chloride into water, stirring and dissolving, and standing for 4-6 hours; mixing a silane coupling agent and ethylene glycol, adding the mixture into a benzoic acid and ammonium chloride aqueous solution, uniformly stirring, standing for 2 hours and barreling for later use;
the anti-shelling precoated sand additive comprises, by weight, 5-8% of a silane coupling agent, 2-5% of benzoic acid, 20-35% of ethylene glycol, 3-6% of ammonium chloride and the balance of water.
2. The method for preparing unshelling coated sand according to claim 1, wherein the silane coupling agent is γ -aminopropyltriethoxysilane.
3. The method for preparing unshelling coated sand according to claim 1, wherein: the content of silicon dioxide in the raw sand is more than 90%.
4. The method for preparing unshelling coated sand according to claim 1, wherein: the raw sand comprises 70% of scrubbing sand with the grain diameter of 70/140 meshes and 30% of scrubbing sand with the grain diameter of 50/100 meshes.
5. The method for preparing unshelling coated sand according to claim 1, wherein: the polymerization speed of the phenolic resin is 20-22 seconds.
6. The method for preparing unshelling coated sand according to claim 1, wherein: the time from sand release to sand production is controlled between 150 seconds and 160 seconds.
7. The method for preparing unshelling coated sand according to claim 1, wherein: the rotational speed of the sand mixer in the preparation process is 65-95 r/min.
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| US3814626A (en) * | 1970-05-08 | 1974-06-04 | Quaker Oats Co | Core box |
| JP3794944B2 (en) * | 2000-07-31 | 2006-07-12 | 保土谷アシュランド株式会社 | Manufacturing method of casting mold |
| CN102688977B (en) * | 2012-06-12 | 2014-09-03 | 西峡县众德汽车部件有限公司 | High-strength core-preparing precoated sand and preparation process thereof |
| CN103567357A (en) * | 2013-10-11 | 2014-02-12 | 铜陵市经纬流体科技有限公司 | Anti-vein precoated sand and preparation method thereof |
| CN103586401A (en) * | 2013-11-27 | 2014-02-19 | 吴江市液铸液压件铸造有限公司 | Precoated sand |
| CN103951932B (en) * | 2014-05-12 | 2016-04-06 | 山东圣泉新材料股份有限公司 | Precoated sand phenol resin composition and preparation method thereof |
| CN104014718B (en) * | 2014-06-18 | 2016-08-17 | 承德北雁铸造材料有限公司 | A kind of precoated sand of anti-shelling and preparation method thereof |
| CN105234342B (en) * | 2015-11-17 | 2018-01-23 | 彰武联信金莹铸造材料有限公司 | A kind of high temperature resistance and high strength precoated sand and preparation method thereof |
| CN106493285B (en) * | 2016-10-28 | 2019-03-05 | 东南大学 | A method of improving precoated sand performance |
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