CN117548622B - Precoated sand for selective laser sintering and preparation method thereof - Google Patents
Precoated sand for selective laser sintering and preparation method thereof Download PDFInfo
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- CN117548622B CN117548622B CN202410013958.8A CN202410013958A CN117548622B CN 117548622 B CN117548622 B CN 117548622B CN 202410013958 A CN202410013958 A CN 202410013958A CN 117548622 B CN117548622 B CN 117548622B
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- 239000004576 sand Substances 0.000 title claims abstract description 93
- 238000000110 selective laser sintering Methods 0.000 title claims abstract description 41
- 238000002360 preparation method Methods 0.000 title claims abstract description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 109
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical group [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 claims abstract description 24
- 239000005011 phenolic resin Substances 0.000 claims abstract description 24
- 229920001568 phenolic resin Polymers 0.000 claims abstract description 24
- 239000011230 binding agent Substances 0.000 claims abstract description 18
- 239000012744 reinforcing agent Substances 0.000 claims abstract description 17
- 239000002131 composite material Substances 0.000 claims abstract description 16
- VKYKSIONXSXAKP-UHFFFAOYSA-N hexamethylenetetramine Chemical group C1N(C2)CN3CN1CN2C3 VKYKSIONXSXAKP-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 12
- 238000005266 casting Methods 0.000 claims abstract description 11
- 239000000314 lubricant Substances 0.000 claims abstract description 11
- CJZGTCYPCWQAJB-UHFFFAOYSA-L calcium stearate Chemical group [Ca+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O CJZGTCYPCWQAJB-UHFFFAOYSA-L 0.000 claims abstract description 7
- 239000008116 calcium stearate Substances 0.000 claims abstract description 7
- 235000013539 calcium stearate Nutrition 0.000 claims abstract description 7
- 239000006004 Quartz sand Substances 0.000 claims abstract description 5
- 235000010299 hexamethylene tetramine Nutrition 0.000 claims abstract description 5
- 239000004312 hexamethylene tetramine Substances 0.000 claims abstract description 5
- HGPXWXLYXNVULB-UHFFFAOYSA-M lithium stearate Chemical compound [Li+].CCCCCCCCCCCCCCCCCC([O-])=O HGPXWXLYXNVULB-UHFFFAOYSA-M 0.000 claims abstract description 3
- XOOUIPVCVHRTMJ-UHFFFAOYSA-L zinc stearate Chemical compound [Zn+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O XOOUIPVCVHRTMJ-UHFFFAOYSA-L 0.000 claims abstract description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 28
- 238000000034 method Methods 0.000 claims description 23
- 238000003756 stirring Methods 0.000 claims description 18
- 238000000149 argon plasma sintering Methods 0.000 claims description 15
- 239000002048 multi walled nanotube Substances 0.000 claims description 10
- XQUPVDVFXZDTLT-UHFFFAOYSA-N 1-[4-[[4-(2,5-dioxopyrrol-1-yl)phenyl]methyl]phenyl]pyrrole-2,5-dione Chemical compound O=C1C=CC(=O)N1C(C=C1)=CC=C1CC1=CC=C(N2C(C=CC2=O)=O)C=C1 XQUPVDVFXZDTLT-UHFFFAOYSA-N 0.000 claims description 9
- 238000007639 printing Methods 0.000 claims description 8
- IPJGAEWUPXWFPL-UHFFFAOYSA-N 1-[3-(2,5-dioxopyrrol-1-yl)phenyl]pyrrole-2,5-dione Chemical compound O=C1C=CC(=O)N1C1=CC=CC(N2C(C=CC2=O)=O)=C1 IPJGAEWUPXWFPL-UHFFFAOYSA-N 0.000 claims description 7
- 238000010438 heat treatment Methods 0.000 claims description 6
- 229920001721 polyimide Polymers 0.000 claims description 6
- 239000009719 polyimide resin Substances 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 5
- 238000001035 drying Methods 0.000 claims description 2
- 238000007873 sieving Methods 0.000 claims description 2
- 239000000126 substance Substances 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 abstract description 22
- 238000010146 3D printing Methods 0.000 abstract description 8
- 230000007547 defect Effects 0.000 abstract description 3
- 238000000465 moulding Methods 0.000 abstract description 3
- 230000001476 alcoholic effect Effects 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 229920001169 thermoplastic Polymers 0.000 description 4
- 239000004416 thermosoftening plastic Substances 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 238000007528 sand casting Methods 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000003110 molding sand Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000002041 carbon nanotube Substances 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000011417 postcuring Methods 0.000 description 1
- 238000003892 spreading Methods 0.000 description 1
Classifications
-
- 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
-
- 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
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/02—Sand moulds or like moulds for shaped castings
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/12—Treating moulds or cores, e.g. drying, hardening
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y10/00—Processes of additive manufacturing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y70/00—Materials specially adapted for additive manufacturing
- B33Y70/10—Composites of different types of material, e.g. mixtures of ceramics and polymers or mixtures of metals and biomaterials
-
- 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
- Y02P10/25—Process efficiency
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
Abstract
The invention provides precoated sand for selective laser sintering, which is used for manufacturing sand molds and sand cores for casting by using a selective laser sintering 3D printing mode; the precoated sand for selective laser sintering comprises the following components: raw sand, a binder, a curing agent, a lubricant and a composite reinforcing agent; wherein: the raw sand is natural quartz sand or precious sand; the binder is phenolic resin, and the addition amount is 1-3% of the mass of the raw sand; the curing agent is hexamethylenetetramine, and the addition amount is 10-25% of the mass of the binder; the lubricant is calcium stearate or lithium stearate or zinc stearate, and the addition amount of the lubricant is 2-8% of the mass of the binder. The invention also discloses a preparation method of the precoated sand for selective laser sintering. The sand mould and the sand core for casting prepared by the invention have compact structure, few defects and high molding strength.
Description
Technical Field
The invention relates to the technical field of manufacturing of foundry sand cores, in particular to precoated sand for selective laser sintering and a preparation method thereof, and particularly relates to a method for manufacturing foundry sand molds and cores by sintering the precoated sand in a specific area by adopting Selective Laser Sintering (SLS).
Background
In the prior art, sand casting is commonly used for manufacturing metal parts with complex structures and inner cavities, such as automobile engine shells and engine bodies, because the sand casting has the advantages of low raw material cost, wide casting size range, low processing cost and the like. The traditional sand mould (core) manufacturing method has the defects of complex production process, long manufacturing period, and particularly the problems that the casting cannot meet the precision requirement, the cutting allowance is large and the like due to slight deviation of the size of the sand mould (core) in the production of various complex castings, so that a large amount of raw materials are wasted, and the production efficiency and the economic benefit are reduced. Therefore, how to produce high quality sand molds (cores) quickly and efficiently stably is a problem to be solved.
Additive Manufacturing (AM) technology can rapidly manufacture parts having complex shapes without any mold or tool, and can be used to manufacture sand molds having complex external shapes and internal structures in a single piece or in small batches in a short time. Selective area laser sintering (SLS) is one of the additive manufacturing techniques, using a high power laser beam to selectively irradiate the surface of a target powder bed, heating and sintering the powder (i.e., inter-particle fusion) for integral connection, after one layer is completed, lowering the platform by one layer in height, spreading a new layer of powder on the previous surface for the next round of heating and sintering, and stacking layer by layer to finally obtain the part. Compared with the traditional sand casting method, the method can directly complete the complex and huge casting production process on the SLS machine, saves a large number of tooling equipment (forming machine, core making machine, transportation equipment and the like), breaks through the production bottleneck of the traditional sand (core) manufacturing method that the manufacturing difficulty is high and the production period is long.
The Selective Laser Sintering (SLS) technology can realize the rapid molding of complex precise sand molds without a mold. However, at present, due to the special molding mode and process characteristics of the selective laser sintering precoated sand mold, some problems need to be solved, such as balance between the strength and the gas generation amount of the sample, low initial strength of the sample, and need post-curing treatment to improve the strength. The problems may cause damage and deformation of part of the precision structure in the subsequent treatment process in actual production, resulting in ultra-poor dimensional accuracy and reduced surface quality of castings. There is a need to propose a targeted solution to the problem.
Disclosure of Invention
The invention provides precoated sand for selective laser sintering and a preparation method thereof, wherein the precoated sand prepared by the method is used for manufacturing sand molds and sand cores for casting in a Selective Laser Sintering (SLS) 3D printing mode, and a formed part has higher strength and avoids damage and deformation of precise structures of the sand molds and the sand cores in a subsequent process flow.
The technical scheme of the invention is as follows:
the technical key of precoated sand for selective laser sintering is as follows: the method comprises the steps of manufacturing a sand mould and a sand core for casting by using a Selective Laser Sintering (SLS) 3D printing mode; the formed part has higher strength, and the damage and the deformation of the precise structure of the sand mould and the sand core in the subsequent process flow are avoided;
the precoated sand for selective laser sintering comprises the following components: raw sand, a binder, a curing agent, a lubricant and a composite reinforcing agent; wherein:
the raw sand is natural quartz sand or precious sand, etc.;
the binder is phenolic resin, and the addition amount of the binder is 1-3% of the mass of the raw sand;
the curing agent is hexamethylenetetramine (urotropine), and the addition amount of the curing agent is 10-25% of the mass of the binder;
the lubricant is calcium stearate or lithium stearate or zinc stearate, and the addition amount of the lubricant is 2-8% of the mass of the binder;
the addition amount of the composite reinforcing agent is 20-40% of the mass of the binder; the composite reinforcing agent is at least one of multi-wall carbon nano tubes and the following substances: diphenylmethane bismaleimide, m-phenylene bismaleimide, polyimide resin; the diameter of the multi-wall carbon nano tube is 60-100nm, and the length is 5-20 mu m. The addition of the composite reinforcing agent can effectively improve the strength of the formed part and avoid deformation and damage of the selected area laser sintering formed part in the subsequent treatment process due to low initial strength.
The precoated sand for selective laser sintering disclosed by the invention has the following technical contents:
the multi-wall carbon nano tube accounts for 1.5-5% of the total mass of the composite reinforcing agent, and the balance of the composite reinforcing agent is at least one of diphenylmethane bismaleimide, m-phenylene bismaleimide and polyimide resin.
The specific preparation steps and the contents are as follows:
(1) Firstly, phenolic resin serving as a binder and ethanol are mixed according to mass ratio of 1: mixing in proportion 1, heating to 70 ℃ while stirring, and preserving heat until phenolic resin is completely dissolved;
then adding a curing agent, namely hexamethylenetetramine (urotropine), and continuously stirring until the curing agent is completely dissolved to prepare a solution A;
(2) Preheating raw sand in an oven at 70-100 ℃ for 0.5-1 hour, and heating the solution A obtained in the step (1) to 65-75 ℃;
placing preheated raw sand into a sand mixer, adding the heated solution A while stirring, and uniformly stirring; adding a lubricant, uniformly stirring, placing in a baking oven, drying at 70-100 ℃, taking out, crushing and sieving to obtain precoated sand;
(3) Adding a composite reinforcing agent into the precoated sand obtained in the step (2), and uniformly mixing for later use;
(4) Printing a sample by using selective laser sintering equipment to obtain a final sand mould and a sand core for casting; the formed part has higher strength, and the damage and deformation of the precise structure of the sand mould and the sand core in the subsequent process flow are avoided.
Further preferred technical requirements are: when the selected area laser sintering equipment is used for printing the sample, the laser sintering process parameters are set as follows: the laser power is 10-20W, the scanning speed is 1-2m/s, and the preheating temperature is 60-80 ℃.
In summary, the preparation method of the precoated sand for selective laser sintering comprises the following steps: firstly preparing precoated sand for selective laser sintering by using a cold method coating process, then adding a composite reinforcing agent, and uniformly mixing. The composite reinforcing agent is one or more of multiwall carbon nanotubes, diphenylmethane bismaleimide, m-phenylene bismaleimide and polyimide resin.
The beneficial effects of the invention are as follows:
compared with the prior art, the precoated sand prepared by the method provided by the invention has the advantages that two reinforcing agents are added into the traditional phenolic resin precoated sand, so that the precoated sand for selective laser sintering is obtained. The diphenylmethane bismaleimide, the m-phenylene bismaleimide and the polyimide resin cured product have compact structure and few defects, and the strength of the formed part can be greatly improved; the carbon nanotubes can consume the fracture energy in the modes of bridging, fracture, pulling out and the like, so that the strength of the formed part is further improved.
Detailed Description
The invention is further illustrated, but not limited, by the following examples.
Example 1
The phenolic resin ethanol solution comprises the following components in percentage by weight: 500g of phenolic resin, 500g of ethanol and 108g of urotropine.
30kg of raw sand (natural quartz sand) was weighed and put into an oven, and preheated at 90℃for 0.5h. The prepared alcoholic solution of the thermoplastic phenolic resin is heated to 70 ℃. And placing the preheated raw sand into a sand mixer, adding the heated phenolic resin ethanol solution while stirring, and uniformly stirring. 36g of calcium stearate is added, the mixture is placed in an oven after being stirred uniformly, and is taken out after being dried at 90 ℃, crushed and sieved. 96g of diphenylmethane bismaleimide and 4g of multi-wall carbon nano tubes are added and uniformly mixed to obtain precoated sand.
And (3) placing the precoated sand into selective area laser sintering (SLS) 3D printing equipment to manufacture the 8-shaped standard sample. When the selected area laser sintering equipment is used for printing the sample, the laser sintering process parameters are set as follows: the laser power is 10-20W, the scanning speed is 1-2m/s, and the preheating temperature is 60-80 ℃. In this embodiment, the coated sand for laser sintering is printed into a sand mold and a sand core, and the performance of the coated sand is mainly verified.
The test specimen was baked at 200℃for 1 hour and then tested, and its tensile strength was 3.591MPa as measured by an intelligent sand strength tester, and its gas evolution at 850℃was 13.7ml/g as measured by an intelligent gas evolution tester.
Example 2
The phenolic resin ethanol solution comprises the following components in percentage by weight: 500g of phenolic resin, 500g of ethanol and 108g of urotropine.
30kg of raw sand (Baozhu sand) is weighed and put into an oven to be preheated for 0.5h at 90 ℃. The prepared alcoholic solution of the thermoplastic phenolic resin is heated to 70 ℃. And placing the preheated raw sand into a sand mixer, adding the heated phenolic resin ethanol solution while stirring, and uniformly stirring. 36g of calcium stearate is added, the mixture is placed in an oven after being stirred uniformly, and is taken out after being dried at 90 ℃, crushed and sieved. 48g of diphenylmethane bismaleimide, 48g of m-phenylene bismaleimide and 4g of multi-wall carbon nano tubes are added and uniformly mixed to obtain precoated sand.
The precoated sand is put into Selective Laser Sintering (SLS) 3D printing equipment, an 8-shaped standard sample is manufactured, and when the selective laser sintering equipment is used for printing the sample, the laser sintering process parameters are set as follows: the laser power is 10-20W, the scanning speed is 1-2m/s, and the preheating temperature is 60-80 ℃. And (3) printing the precoated sand for laser sintering into a sand mold and a sand core, wherein the performance of the precoated sand is mainly verified.
The test specimen was baked at 200℃for 1 hour, and then tested with an intelligent sand strength tester to give a tensile strength of 4.661MPa, and with an intelligent air-forming tester to give an air-forming rate of 13.5ml/g at 850 ℃.
Example 3
The phenolic resin ethanol solution comprises the following components in percentage by weight: 500g of phenolic resin, 500g of ethanol and 108g of urotropine.
30kg of raw sand (natural quartz sand) was weighed and put into an oven, and preheated at 90℃for 0.5h. The prepared alcoholic solution of the thermoplastic phenolic resin is heated to 70 ℃. And placing the preheated raw sand into a sand mixer, adding the heated phenolic resin ethanol solution while stirring, and uniformly stirring. 36g of calcium stearate is added, the mixture is placed in an oven after being stirred uniformly, and is taken out after being dried at 90 ℃, crushed and sieved. 96g of diphenylmethane bismaleimide and 4.8g of multi-wall carbon nano tubes are added and uniformly mixed to obtain precoated sand.
The precoated sand is put into Selective Laser Sintering (SLS) 3D printing equipment, an 8-shaped standard sample is manufactured, and when the selective laser sintering equipment is used for printing the sample, the laser sintering process parameters are set as follows: the laser power is 10-20W, the scanning speed is 1-2m/s, and the preheating temperature is 60-80 ℃. The test specimen was baked at 200℃for 1 hour, and then tested with an intelligent sand strength tester to give a tensile strength of 3.942MPa, and with an intelligent air-forming tester to give an air-forming rate of 13.9ml/g at 850 ℃.
Comparative example 1
The phenolic resin ethanol solution comprises the following components in percentage by weight: 500g of phenolic resin, 500g of ethanol and 108g of urotropine.
30kg of raw sand is weighed and put into an oven for preheating for 0.5h at 90 ℃. The prepared alcoholic solution of the thermoplastic phenolic resin is heated to 70 ℃. And placing the preheated raw sand into a sand mixer, adding the heated phenolic resin ethanol solution while stirring, and uniformly stirring. 36g of calcium stearate is added, the mixture is placed in an oven after being stirred uniformly, and is taken out after being dried at 90 ℃, crushed and sieved, thus obtaining the precoated sand.
The precoated sand is put into selective area laser sintering (SLS) 3D printing equipment, an 8-shaped standard sample is manufactured, the sample is baked for 1h at 200 ℃ and then tested, the tensile strength of the sample is 3.113MPa by an intelligent molding sand strength meter, and the gas generation amount of the sample at 850 ℃ is 13.1ml/g by an intelligent gas generation tester.
Comparative example 2
30kg of precoated sand prepared by a traditional thermal method is weighed, the precoated sand is placed into selective area laser sintering (SLS) 3D printing equipment, an 8-shaped standard sample is manufactured, the sample is baked for 1h at 200 ℃, the tensile strength of the sample is measured to be 2.385MPa by an intelligent molding sand strength meter, and the gas generation amount of the sample at 850 ℃ is measured to be 16.5ml/g by an intelligent gas generation tester.
The invention is not a matter of the known technology.
The above embodiments are provided to illustrate the technical concept and features of the present invention and are intended to enable those skilled in the art to understand the content of the present invention and implement the same, and are not intended to limit the scope of the present invention. All equivalent changes or modifications made in accordance with the spirit of the present invention should be construed to be included in the scope of the present invention.
Claims (4)
1. The precoated sand for selective laser sintering is characterized in that: the precoated sand for selective laser sintering comprises the following components: raw sand, a binder, a curing agent, a lubricant and a composite reinforcing agent; wherein:
the raw sand is natural quartz sand or precious sand;
the binder is phenolic resin, and the addition amount of the binder is 1-3% of the mass of the raw sand;
the curing agent is hexamethylenetetramine, and the addition amount of the curing agent is 10-25% of the mass of the binder;
the lubricant is calcium stearate or lithium stearate or zinc stearate, and the addition amount of the lubricant is 2-8% of the mass of the binder;
the addition amount of the composite reinforcing agent is 20-40% of the mass of the binder; the composite reinforcing agent is at least one of multi-wall carbon nano tubes and the following substances: diphenylmethane bismaleimide, m-phenylene bismaleimide, polyimide resin;
the diameter of the multi-wall carbon nano tube is 60-100nm, and the length is 5-20 mu m.
2. The selective laser sintering precoated sand as set forth in claim 1, wherein: the multi-wall carbon nano tube accounts for 1.5-5% of the total mass of the composite reinforcing agent, and the balance of the composite reinforcing agent is at least one of diphenylmethane bismaleimide, m-phenylene bismaleimide and polyimide resin.
3. The method for preparing precoated sand for selective laser sintering according to claim 1, wherein the method comprises the following steps: the specific preparation steps and the contents are as follows:
(1) Firstly, phenolic resin serving as a binder and ethanol are mixed according to mass ratio of 1: mixing in proportion 1, heating to 70 ℃ while stirring, and preserving heat until phenolic resin is completely dissolved;
then adding a curing agent, namely hexamethylenetetramine, and continuously stirring until the curing agent is completely dissolved to prepare a solution A;
(2) Preheating raw sand in an oven at 70-100 ℃ for 0.5-1 hour, and heating the solution A obtained in the step (1) to 65-75 ℃;
placing preheated raw sand into a sand mixer, adding the heated solution A while stirring, and uniformly stirring; adding a lubricant, uniformly stirring, placing in a baking oven, drying at 70-100 ℃, taking out, crushing and sieving to obtain precoated sand;
(3) Adding a composite reinforcing agent into the precoated sand obtained in the step (2), and uniformly mixing for later use;
(4) And printing the sample by using a selective laser sintering device to obtain the final sand mould and sand core for casting.
4. A method for preparing precoated sand for selective laser sintering according to claim 3, wherein:
when the selected area laser sintering equipment is used for printing the sample, the laser sintering process parameters are set as follows: the laser power is 10-20W, the scanning speed is 1-2m/s, and the preheating temperature is 60-80 ℃.
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Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104235237A (en) * | 2014-05-09 | 2014-12-24 | 石家庄东大汇通新材料有限公司 | Road vehicle brake disc made of carborundum foamed ceramics/aluminum alloy composite materials and production method of road vehicle brake disc |
| CN104962276A (en) * | 2015-06-26 | 2015-10-07 | 西安理工大学 | Modified carbon nano-tube touching resin pre-coated-sand propping agent and preparing method thereof |
| CN105195667A (en) * | 2015-09-21 | 2015-12-30 | 济南大学 | Preparation method of 3D printing rapid-prototyping precoated sand |
| CN105542166A (en) * | 2016-03-02 | 2016-05-04 | 江汉大学 | Selective laser sintered polyimide powder and preparation method thereof |
| CN108296442A (en) * | 2017-10-27 | 2018-07-20 | 柳州市柳晶科技股份有限公司 | A kind of 3D printing precoated sand moulding process |
| CN113441677A (en) * | 2021-06-18 | 2021-09-28 | 浙江瓯赛汽车部件铸造有限公司 | Casting process of precoated sand for producing turbine box body |
| CN115837445A (en) * | 2023-01-10 | 2023-03-24 | 南昌航空大学 | Preparation method of sand mold/core for titanium alloy casting based on 3D printing |
| CN115945641A (en) * | 2023-01-10 | 2023-04-11 | 北京航空材料研究院股份有限公司 | Molding sand preparation for titanium alloy sand mold casting and selective laser sintering forming method of composite sand mold/core thereof |
| CN116039078A (en) * | 2022-11-16 | 2023-05-02 | 四川大学 | Method for 3D printing of polymer composite material powder bed through inkjet sintering and product thereof |
| CN116099977A (en) * | 2022-12-13 | 2023-05-12 | 北京仁创砂业铸造材料有限公司 | High-melting-point precoated sand and preparation method thereof |
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Patent Citations (10)
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| CN104235237A (en) * | 2014-05-09 | 2014-12-24 | 石家庄东大汇通新材料有限公司 | Road vehicle brake disc made of carborundum foamed ceramics/aluminum alloy composite materials and production method of road vehicle brake disc |
| CN104962276A (en) * | 2015-06-26 | 2015-10-07 | 西安理工大学 | Modified carbon nano-tube touching resin pre-coated-sand propping agent and preparing method thereof |
| CN105195667A (en) * | 2015-09-21 | 2015-12-30 | 济南大学 | Preparation method of 3D printing rapid-prototyping precoated sand |
| CN105542166A (en) * | 2016-03-02 | 2016-05-04 | 江汉大学 | Selective laser sintered polyimide powder and preparation method thereof |
| CN108296442A (en) * | 2017-10-27 | 2018-07-20 | 柳州市柳晶科技股份有限公司 | A kind of 3D printing precoated sand moulding process |
| CN113441677A (en) * | 2021-06-18 | 2021-09-28 | 浙江瓯赛汽车部件铸造有限公司 | Casting process of precoated sand for producing turbine box body |
| CN116039078A (en) * | 2022-11-16 | 2023-05-02 | 四川大学 | Method for 3D printing of polymer composite material powder bed through inkjet sintering and product thereof |
| CN116099977A (en) * | 2022-12-13 | 2023-05-12 | 北京仁创砂业铸造材料有限公司 | High-melting-point precoated sand and preparation method thereof |
| CN115837445A (en) * | 2023-01-10 | 2023-03-24 | 南昌航空大学 | Preparation method of sand mold/core for titanium alloy casting based on 3D printing |
| CN115945641A (en) * | 2023-01-10 | 2023-04-11 | 北京航空材料研究院股份有限公司 | Molding sand preparation for titanium alloy sand mold casting and selective laser sintering forming method of composite sand mold/core thereof |
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