Inorganic binder sand hardening process and applications

Abstract

The application provides an inorganic binder sand hardening process and application. The method comprises the following steps: hardening the formed inorganic binder sand by one of the following modes: mode one, hardening the formed inorganic binder sand by blowing in vaporized organic curing agent and at least one gas in CO2 and compressed air; mode two, hardening the formed inorganic binder sand by blowing in CO2 and compressed air for primary hardening, and then immersing the inorganic binder sand in organic curing agent for secondary hardening; mode three, hardening the formed inorganic binder sand by immersing the inorganic binder sand in organic curing agent; mode four, hardening the formed inorganic binder sand by spraying organic curing agent on the surface of the inorganic binder sand; or the method comprises the following steps: forming the inorganic binder sand by layer-by-layer 3D printing and realizing hardening at the same time. The method can greatly improve the hardening rate and quality of the inorganic binder sand.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of casting, in particular to an inorganic binder sand hardening process method and application. BACKGROUND

[0002] The current casting binder is mainly phenolic resin and furan resin organic matter, and the organic matter is used together with acid curing agent during hardening. During the process of molding, core making and metal liquid pouring into the core, the organic matter will decompose and produce toxic gas, which will harm the operators and cause environmental pollution.

[0003] At present, the inorganic binder sand for casting is mainly water glass sand. The water glass binder is an inorganic material and is non-toxic and harmless. The water glass sand can be hardened by blowing carbon dioxide, heating (mold heating, heating furnace or microwave heating), carbon dioxide + compressed air composite blowing hardening and organic ester hardening, and has the technical characteristics of non-toxic and environmental protection. However, the above water glass sand hardening technologies have the following shortcomings:

[0004] The carbon dioxide blowing hardening alone is prone to overblowing, and the water glass addition amount is high (4-8%). The sand core after casting has poor collapsibility and it is difficult to regenerate the old sand. The heating hardening process can reduce the water glass addition amount to 2.0-3.0%, but it requires uninterrupted and constant temperature input, which has high energy consumption. The carbon dioxide + compressed air composite hardening needs to blow in compressed air or other inert gases during or after the completion of carbon dioxide blowing, which can effectively avoid the overblowing of carbon dioxide, but the overall hardening time is relatively long, which affects the production efficiency. The organic ester self-hardening water glass sand process is limited by the slow overall hardening speed, poor sand flowability and low efficient core making production. SUMMARY

[0005] The purpose of the present application is to provide an inorganic binder sand hardening process method, which can greatly improve the hardening rate and quality of inorganic binder sand, reduce the use amount of inorganic binder sand, and does not use furan resin and phenolic resin organic binder. The method has the advantages of low gas emission, green environmental protection, high strength, good collapsibility and the like. Through the technology involved in the present application, the inorganic core 3D printing technology can be realized without the high energy consumption process such as heating and microwave heating, thereby achieving energy saving and emission reduction.

[0006] To achieve the above technical purposes, the technical solutions adopted by the present application are as follows:

[0007] In a first aspect, the present application provides an inorganic binder sand hardening process method, which comprises: hardening the formed inorganic binder sand by one of the following methods:

[0008] In the first mode, the shaped inorganic binder sand is hardened by blowing at least one of vaporized organic curing agent, CO2 and compressed air;

[0009] In the second mode, the shaped inorganic binder sand is first hardened by blowing CO2 and compressed air, and then is secondly hardened by immersing the inorganic binder sand in organic curing agent;

[0010] In the third mode, the shaped inorganic binder sand is hardened by immersing the inorganic binder sand in organic curing agent;

[0011] In the fourth mode, the shaped inorganic binder sand is hardened by spraying organic curing agent on the surface of the shaped inorganic binder sand;

[0012] Alternatively, the method comprises: forming the inorganic binder sand by layer-by-layer 3D printing while hardening the inorganic binder sand.

[0013] The organic curing agent is selected from at least one of methanol, ethanol, ethylene glycol, propanol, acetonitrile and acetone.

[0014] Preferably, in the first mode, the shaped inorganic binder sand is blown with at least one of vaporized organic curing agent, CO2 and compressed air in one of the following ways:

[0015] In the first mode, the vaporized organic curing agent, CO2 and compressed air are blown in any order;

[0016] In the second mode, the vaporized organic curing agent and compressed air are blown in any order;

[0017] In the third mode, the vaporized organic curing agent and CO2 are blown in any order.

[0018] Preferably, in the first mode, the vaporized organic curing agent is blown at a pressure of 0.05 MPa to 0.5 MPa for 5 s to 50 s; and / or, the CO2 is blown at a pressure of 0.05 MPa to 0.5 MPa for 5 s to 90 s; and / or, the compressed air is blown at a pressure of 0.05 MPa to 0.5 MPa for 5 s to 40 s.

[0019] Preferably, in the second mode, the CO2 is blown at a pressure of 0.05 MPa to 0.5 MPa for 5 s to 90 s; and / or, the compressed air is blown at a pressure of 0.05 MPa to 0.5 MPa for 5 s to 40 s; and / or, the inorganic binder sand is immersed in the organic curing agent for 0.5 s to 600 s for the second hardening.

[0020] Preferably, in the third mode, the time for immersing the shaped inorganic binder sand into the organic curing agent is 0.5s-600s.

[0021] Preferably, in the fourth mode, the shaped inorganic binder sand is surface sprayed with the organic curing agent for hardening, and the spraying frequency is 1-10 times.

[0022] Preferably, the raw material composition of the inorganic binder sand comprises raw sand, binder, and hardening accelerator; the binder is added in an amount of 2%-3% of the mass of the raw sand, and the hardening accelerator is added in an amount of 0-50% of the mass of the binder; more preferably, the binder is water glass or modified water glass.

[0023] Preferably, the hardening of the inorganic binder sand is achieved by one of the following modes:

[0024] Mode 1), the raw sand is laid on a 3D printing instrument, and then the binder and the organic curing agent are sprayed on the surface of the raw sand in sequence, and 3D scanning is performed; the foregoing process is repeated until the 3D printing is completed;

[0025] Mode 2), the raw sand and the binder are mixed, and then the mixture is laid on a 3D printing instrument, and the organic curing agent is sprayed, and 3D scanning is performed; the foregoing process is repeated until the 3D printing is completed;

[0026] More preferably, the mass ratio of the raw sand, the binder, and the organic curing agent is controlled to be 100:2-3:0.1-1.0.

[0027] More preferably, the binder is water glass or modified water glass, and the addition amount is 2%-3% of the mass of the raw sand.

[0028] Preferably, the hardening accelerator is added to the raw sand, and the addition amount of the hardening accelerator is 1-50% of the mass of the binder; more preferably, the hardening accelerator is at least one of bauxite, crystalline silicon dioxide, non-crystalline silicon dioxide, fumed silicon dioxide, silicon micro powder, micro silicon powder, wollastonite powder, and surface-modified silicon dioxide.

[0029] In a second aspect, the application provides a method for repairing and / or hardening the surface of inorganic binder sand, which is performed by the fourth mode in the process method of the first aspect.

[0030] The application has the following advantages:

[0031] In one aspect, the inorganic binder sand hardening process method of the present application can solve the problems of high addition amount, high energy consumption and low production efficiency of the inorganic binder sand, and the hardening process does not release toxic substances, the hardening speed is fast, the energy consumption is low, the prepared sand core has high strength, no toxic and harmful, irritating substances are generated during hardening and casting, the dehydration process is fast, the labor environment can be improved, and the environment is protected.

[0032] In another aspect, the inorganic binder sand hardening process method of the present application can also be used for repairing sand molds and cores, and preparing inorganic cores by 3D printing technology, and the whole process does not have high energy consumption process such as heating, so that the energy saving and emission reduction target is achieved.

[0033] In a third aspect, the inorganic binder sand, i.e. water glass sand, obtained in the embodiments of the present application has a higher tensile strength of the "8" sample prepared according to the casting industry standard, especially excellent immediate strength, and the highest immediate strength can be above 1.3 MPa, the highest 24h tensile strength can be above 2.0 MPa, the immediate strength can generally be above 0.4 MPa, and the 24h tensile strength can generally be above 0.7 MPa.

[0034] In addition, the inorganic binder sand hardening process method of the present application applied to the repair and hardening of sand molds and cores can obtain sand molds and cores with a surface hardness improved by more than 6.4%, and a 24h tensile strength unchanged or even better. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The figure is the surface structure diagram of the sand core before and after the treatment of the embodiment 28 of the present application.

[0036] Figure 2 The figure is the actual object diagram of the sand core surface repair using the water-based repair mud. DETAILED DESCRIPTION

[0037] In the description of the present application, it should be noted that the specific conditions are not indicated in the embodiments, and the conventional conditions or the conditions recommended by the manufacturer are used. The reagents or instruments used are not indicated by the manufacturer, and are conventional products that can be purchased on the market.

[0038] In the present application, the molding sand includes a casting binder and raw sand, and the raw sand is Daling scrubbing sand. The measurement method of the strength and gas evolution of the prepared molding sand is determined according to GB / T 2684-2009 Casting Sand and Mixture Test Method.

[0039] The modified water glass used in the embodiment of the present application is modified by the following method: the following substances are sequentially added into a reaction container in the order of mass ratio: water glass: sodium hydroxide: potassium hydroxide: sorbitol: sodium hexametaphosphate: glucoside: polyvinyl alcohol = 100:3:4:5:5:0.5:0.5, and stirred uniformly, and then obtained.

[0040] In addition, other modified water glasses can also be used in the present application, such as: the modulus is adjusted by sodium hydroxide, potassium hydroxide, lithium hydroxide, citric acid, ammonium chloride, etc., the strength is improved by organic alcohols such as glucose, sorbitol, and xylitol; the collapse property is improved by sodium pyrophosphate, sodium hexametaphosphate, sodium dihydrogen phosphate, and aluminum dihydrogen phosphate; the viscosity of the water glass and the flowability of the molding sand are improved by anionic or cationic surfactants; the moisture absorption resistance is improved by organic polymers such as PVB, EVA, polyvinyl alcohol, starch, polyacrylic acid, and sodium polyacrylate; in addition to the above-mentioned component modification, the modification effect can also be optimized by changing the temperature, external magnetic field, high temperature and high pressure, etc.

[0041] The surface-modified silicon dioxide used in the embodiment of the present application is modified by the following method: the dried silicon dioxide powder is weighed and added into a high-speed mixer, a measured amount of oligomeric short-chain alkylsilane KH550 (KH560 can also be used, and a mixture of KH550 and KH560 can also be used) is added, the amount of KH550 added is 0.5% of the silicon dioxide powder (the amount added can be controlled between 0.1-1.0%), the modification time is 20 minutes, the stirring speed is 1250 r / min, and the reaction product is discharged by low-speed stirring. The surface of the silicon dioxide powder has a large number of active hydroxyl groups, and has strong hydrophilicity, which makes it easy to form agglomerates or secondary aggregates, which is not conducive to its dispersion in materials, and further affects the structure and performance of the materials. Therefore, it is necessary to modify the surface of the silicon dioxide powder to ensure its stable storage and improve its dispersibility in products, etc. In addition, other modified silicon dioxide can also be used in the present application, such as: silane coupling agent modification, organic polymer modification, modification with other alkaline metal hydroxides and oxides by high-speed ball milling with a ball mill or low-temperature sintering, etc.

[0042] The present application will be further described below in conjunction with the drawings and specific embodiments. Those skilled in the art can refer to the content herein to appropriately improve the process parameters. It should be particularly pointed out that all similar substitutions and changes are obvious to those skilled in the art, and they are considered to be included in the present application. The method and application of the present application have been described by the preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application herein without departing from the content, spirit and scope of the present application, to realize and apply the present application technology. In addition, the following embodiments are only used to illustrate the present application, but not to limit the present application.

[0043] Example 1

[0044] The present example provides a process for hardening inorganic binder sand, comprising the following steps:

[0045] Step 1, heat the organic curing agent ethanol to vaporization, at 0.1 MPa, pass compressed air into the vaporized organic curing agent to carry out ethanol, and then pass into the inorganic binder sand core sample for hardening, after blowing for 30 s, close the compressed air gas pipeline;

[0046] Step 2, at 0.15 MPa, pass CO2 gas into the inorganic binder sand core sample, blow for 60 s, and close the CO2 gas pipeline;

[0047] Step 3, at 0.2 MPa, pass compressed air into the inorganic binder sand core sample, blow for 20 s, after blowing, test the tensile strength of the sample with a hydraulic testing machine, measure the instantaneous strength within 60 s to take the average value of the sample; after placing the sample in the room for 24 h, test the final strength of the sample. The results are shown in Table 1 (Examples 2-27, Comparative Examples 1-2 are the same).

[0048] The preparation process of the inorganic binder sand core sample includes: mixing sand 1000 g, water glass for casting with a modulus of 2.5 20 g, crystalline silica 4 g, to make sand and core, take an appropriate amount of mixture and place it in an "8" shaped mold, use a hammering type sample making machine to make sample, make 5 samples for parallel test, Examples 1-27, Comparative Examples 1-2 are the same.

[0049] Example 2

[0050] The present example provides a process for hardening inorganic binder sand, comprising the following steps:

[0051] Step 1, heat the organic curing agent n-propanol to vaporization, at 0.2 MPa, pass compressed air into the vaporized organic curing agent to carry out n-propanol, and then pass into the inorganic binder sand core sample for hardening, after blowing for 30 s, close the compressed air gas pipeline;

[0052] Step 2, at 0.15 MPa, pass CO2 gas into the inorganic binder sand core sample, blow for 90 s, and close the CO2 gas pipeline;

[0053] Step 3, at 0.2 MPa, pass compressed air into the inorganic binder sand core sample, blow for 30 s, after blowing, test the tensile strength of the sample with a hydraulic testing machine, measure the instantaneous strength within 60 s to take the average value of the sample; after placing the sample in the room for 24 h, test the final strength of the sample. The results are shown in Table 1.

[0054] The preparation process of the inorganic binder sand core sample includes the following steps: 1000g of Dalin scrubbing sand, 20g of casting sodium silicate with a modulus of 2.0, and 4g of microsilica powder are mixed and sand core is prepared, an appropriate amount of the mixture is placed in an "8" shaped mold, and a sample is prepared by using a hammering type sample preparation machine, and the sample is obtained.

[0055] Example 3

[0056] The embodiment provides an inorganic binder sand hardening process method, which comprises the following steps:

[0057] Step 1, the organic curing agent ethanol is heated to vaporization, under 0.15MPa, compressed air is introduced into the vaporized organic curing agent to carry out ethanol, and then introduced into the inorganic binder sand core sample for hardening, after blowing for 30s, the compressed air gas pipeline is closed;

[0058] Step 2, under 0.2MPa, CO2 gas is introduced into the inorganic binder sand core sample, blowing for 60s, and the CO2 gas pipeline is closed;

[0059] Step 3, under 0.15MPa, compressed air is introduced into the inorganic binder sand core sample, blowing for 30s, after blowing, the liquid pressure testing machine is used to test the tensile strength of the sample, the average value of the sample is measured within 60s; the sample is placed in the room for 24h, and the final strength of the sample is tested. The results are shown in Table 1.

[0060] The preparation process of the inorganic binder sand core sample includes the following steps: 1000g of Dalin scrubbing sand, 20g of casting sodium silicate with a modulus of 2.0, and 4g of microsilica powder are mixed and sand core is prepared, an appropriate amount of the mixture is placed in an "8" shaped mold, and a sample is prepared by using a hammering type sample preparation machine, and the sample is obtained.

[0061] Example 4

[0062] The embodiment provides an inorganic binder sand hardening process method, which comprises the following steps:

[0063] Step 1, under 0.2MPa, CO2 gas is introduced into the inorganic binder sand core sample, blowing for 60s, and the CO2 gas pipeline is closed;

[0064] Step 2, under 0.15MPa, compressed air is introduced into the inorganic binder sand core sample, blowing for 50s, and the compressed air gas pipeline is closed;

[0065] Step 3, the organic curing agent methanol is heated to vaporization, compressed air is introduced into the vaporized organic curing agent to carry out the methanol, and then the inorganic binder sand core sample is introduced to harden, after blowing for 40s, after the blowing is finished, the tensile strength of the sample is tested by a liquid pressure testing machine, the average value of the sample is taken within 60s to test the instantaneous strength, and the final strength of the sample is tested after the sample is placed indoors for 24h. The results are shown in Table 1.

[0066] The preparation process of the inorganic binder sand core sample includes the following steps: 1000g of Dalin scrubbing sand, 20g of a modulus of 2.0 water glass for casting, and 10g of fumed silica are mixed and sand core is prepared, an appropriate amount of the mixture is placed in an "8" type mold, and a sample is prepared by using a hammering type sample preparation machine, and the sample is obtained.

[0067] Example 5

[0068] The embodiment provides an inorganic binder sand hardening process method, including the following steps:

[0069] Step 1, the organic curing agent ethanol is heated to vaporization, compressed air is introduced into the vaporized organic curing agent to carry out the ethanol, and then the inorganic binder sand core sample is introduced to harden, after blowing for 30s, the compressed air gas pipeline is closed;

[0070] Step 2, under the condition of 0.2MPa, CO2 gas is introduced into the inorganic binder sand core sample, blowing for 60s, after the blowing is finished, the tensile strength of the sample is tested by a liquid pressure testing machine, the average value of the sample is taken within 60s to test the instantaneous strength, and the final strength of the sample is tested after the sample is placed indoors for 24h. The results are shown in Table 1.

[0071] The preparation process of the inorganic binder sand core sample includes the following steps: 1000g of Dalin scrubbing sand, 20g of a modulus of 2.0 water glass for casting, and 10g of fumed silica are mixed and sand core is prepared, an appropriate amount of the mixture is placed in an "8" type mold, and a sample is prepared by using a hammering type sample preparation machine, and the sample is obtained.

[0072] Example 6

[0073] The embodiment provides an inorganic binder sand hardening process method, including the following steps:

[0074] Step 1, the organic curing agent ethanol is heated to vaporization, compressed air is introduced into the vaporized organic curing agent to carry out the ethanol, and then the inorganic binder sand core sample is introduced to harden, after blowing for 30s, the compressed air gas pipeline is closed;

[0075] Step 2, under 0.15 MPa, compressed air is introduced into the inorganic binder sand core sample, and blowing is performed for 30 s. After blowing is completed, the tensile strength of the sample is tested by using a hydraulic testing machine. The average value of the sample is measured within 60 s. After the sample is placed indoors for 24 h, the final strength of the sample is tested. The results are shown in Table 1.

[0076] The preparation process of the inorganic binder sand core sample includes the following steps: 1000 g of Dalin scrubbed sand, 20 g of a modulus of 2.0 sodium silicate for casting, and 10 g of crystalline silica are mixed and sand core molding is performed. An appropriate amount of the mixture is placed in an "8" shaped mold, and a hammering type sample preparation machine is used to prepare the sample.

[0077] Example 7

[0078] The present example provides an inorganic binder sand hardening process method, which includes the following steps:

[0079] Step 1, the organic curing agent acetone is heated to vaporization. Under 0.15 MPa, compressed air is introduced into the vaporized organic curing agent to carry out acetone, and then introduced into the inorganic binder sand core sample for hardening. After blowing for 60 s, the compressed air gas pipeline is closed.

[0080] Step 2, under 0.15 MPa, compressed air is introduced into the inorganic binder sand core sample, and blowing is performed for 30 s. After blowing is completed, the tensile strength of the sample is tested by using a hydraulic testing machine. The average value of the sample is measured within 60 s. After the sample is placed indoors for 24 h, the final strength of the sample is tested. The results are shown in Table 1.

[0081] The preparation process of the inorganic binder sand core sample includes the following steps: 1000 g of Dalin scrubbed sand, 20 g of a modulus of 2.0 sodium silicate for casting, and 10 g of crystalline silica are mixed and sand core molding is performed. An appropriate amount of the mixture is placed in an "8" shaped mold, and a hammering type sample preparation machine is used to prepare the sample.

[0082] Example 8

[0083] The present example provides an inorganic binder sand hardening process method, which includes the following steps:

[0084] Step 1, under 0.15 MPa, compressed air is introduced into the inorganic binder sand core sample, and blowing is performed for 30 s. After blowing is completed, the tensile strength of the sample is tested by using a hydraulic testing machine. The average value of the sample is measured within 60 s. After the sample is placed indoors for 24 h, the final strength of the sample is tested. The results are shown in Table 1.

[0085] Step 2, under 0.2 MPa, CO2 gas is introduced into the inorganic binder sand core sample, and blowing is performed for 60 s. The CO2 gas pipeline is closed.

[0086] Step 3, the organic curing agent ethanol is heated to vaporization, compressed air is introduced into the vaporized organic curing agent to carry out the ethanol, and then the inorganic binder sand core sample is introduced to harden, the blowing time is 30s, after the blowing is completed, the tensile strength of the sample is tested by using a hydraulic testing machine, the average value of the sample is measured within 60s, the sample is placed in the room for 24h, and the final strength of the sample is tested. The results are shown in Table 1.

[0087] The preparation process of the inorganic binder sand core sample includes the following steps: 1000g of Dalin scrubbing sand, 20g of modulus 2.0 water glass for casting, and 10g of crystalline silica are mixed and sand core is prepared, an appropriate amount of the mixture is placed in an "8" shaped mold, and a sample is prepared by using a hammering type sample preparation machine.

[0088] Example 9

[0089] The embodiment provides an inorganic binder sand hardening process method, including the following steps:

[0090] Step 1, the organic curing agent ethanol is heated to vaporization, compressed air is introduced into the vaporized organic curing agent to carry out the ethanol, and then the inorganic binder sand core sample is introduced to harden, the blowing time is 30s,

[0091] Step 2, compressed air is introduced into the inorganic binder sand core sample under 0.15MPa, the blowing time is 30s, and the compressed air pipeline is closed;

[0092] Step 3, CO2 gas is introduced into the inorganic binder sand core sample under 0.2MPa, the blowing time is 60s, after the blowing is completed, the tensile strength of the sample is tested by using a hydraulic testing machine, the average value of the sample is measured within 60s, the sample is placed in the room for 24h, and the final strength of the sample is tested. The results are shown in Table 1.

[0093] The preparation process of the inorganic binder sand core sample includes the following steps: 1000g of Dalin scrubbing sand, 20g of modulus 2.0 water glass for casting, and 10g of crystalline silica are mixed and sand core is prepared, an appropriate amount of the mixture is placed in an "8" shaped mold, and a sample is prepared by using a hammering type sample preparation machine.

[0094] Example 10

[0095] The embodiment provides an inorganic binder sand hardening process method, including the following steps:

[0096] Step 1, CO2 gas is introduced into the inorganic binder sand core sample under 0.2MPa, the blowing time is 60s, and the CO2 gas pipeline is closed;

[0097] Step 2, heat the organic curing agent ethanol to vaporization, under 0.15 MPa, compressed air is introduced into the organic curing agent after vaporization to take out ethanol, then the inorganic binder sand core sample is introduced to harden, blowing for 30 s, after blowing, the tensile strength of the sample is tested by a hydraulic testing machine, the average value of the sample is taken within 60 s to measure the instantaneous strength; the final strength of the sample is tested after the sample is placed in the room for 24 h. The results are shown in Table 1.

[0098] The preparation process of the inorganic binder sand core sample includes: 1000 g of Dalin scrubbing sand, 20 g of water glass with a modulus of 2.0 for foundry use, and 10 g of crystalline silica are mixed and sand core is prepared, an appropriate amount of the mixture is placed in an "8" shaped mold, and a sample is prepared by using a hammering type sample preparation machine, and the sample is obtained.

[0099] Example 11

[0100] The embodiment provides an inorganic binder sand hardening process method, including the following steps:

[0101] Step 1, under 0.2 MPa, CO2 gas is introduced into the inorganic binder sand core sample, blowing for 30 s, and the CO2 gas pipeline is closed;

[0102] Step 2, heat the organic curing agent ethanol to vaporization, under 0.15 MPa, compressed air is introduced into the organic curing agent after vaporization to take out ethanol, then the inorganic binder sand core sample is introduced to harden, blowing for 30 s, after blowing, the tensile strength of the sample is tested by a hydraulic testing machine, the average value of the sample is taken within 60 s to measure the instantaneous strength; the final strength of the sample is tested after the sample is placed in the room for 24 h. The results are shown in Table 1.

[0103] The preparation process of the inorganic binder sand core sample includes: 1000 g of Dalin scrubbing sand, 20 g of water glass with a modulus of 2.0 for foundry use, and 10 g of crystalline silica are mixed and sand core is prepared, an appropriate amount of the mixture is placed in an "8" shaped mold, and a sample is prepared by using a hammering type sample preparation machine, and the sample is obtained.

[0104] Example 12

[0105] The embodiment provides an inorganic binder sand hardening process method, including the following steps:

[0106] Step 1, under 0.2 MPa, CO2 gas is introduced into the inorganic binder sand core sample, blowing for 30 s, and the CO2 gas pipeline is closed;

[0107] Step 2, under 0.15 MPa, compressed air is introduced into the inorganic binder sand core sample, blowing for 30 s, and the compressed air gas pipeline is closed;

[0108] Step 3, after the end of blowing, the mold is immersed in organic curing agent anhydrous ethanol, soaking time 60s, after soaking, the tensile strength of the sample is tested by hydraulic testing machine, the average value of the sample is measured within 60s; the sample is placed in the room for 24h, and the final strength of the sample is tested. The results are shown in Table 1.

[0109] The preparation process of the inorganic binder sand core sample includes: mixing sand with 1000g of Dalin scrubbing sand, 20g of casting water glass with a modulus of 2.0, and 10g of crystalline silica to make a sand core, taking an appropriate amount of the mixture and placing it in an "8" shaped mold, and using a hammering type sample making machine to make a sample.

[0110] Example 13

[0111] The present embodiment provides an inorganic binder sand hardening process method, which includes the following steps:

[0112] The inorganic binder sand is immersed in organic curing agent anhydrous methanol, the soaking time is 10s, after soaking, the tensile strength of the sample is tested by hydraulic testing machine, the average value of the sample is measured within 60s; the sample is placed in the room for 24h, and the final strength of the sample is tested. The results are shown in Table 1.

[0113] The preparation process of the inorganic binder sand core sample is the same as that of Example 8.

[0114] Example 14

[0115] The present embodiment provides an inorganic binder sand hardening process method, which is different from Example 13 in that the organic curing agent is ethanol, and the soaking time is 50s.

[0116] Example 15

[0117] The present embodiment provides an inorganic binder sand hardening process method, which is different from Example 14 in that the soaking time is 10s.

[0118] Example 16

[0119] The present embodiment provides an inorganic binder sand hardening process method, which is different from Example 14 in that the soaking time is 100s.

[0120] Example 17

[0121] The present embodiment provides an inorganic binder sand hardening process method, which is different from Example 13 in that the organic curing agent is ethylene glycol, and the soaking time is 90s.

[0122] Example 18

[0123] The present embodiment provides an inorganic binder sand hardening process method, which is different from Example 13 in that the organic curing agent is n-propanol, and the soaking time is 40s.

[0124] Example 19

[0125] The present example provides a sand hardening process method of inorganic binder, which is different from example 13 in that the organic curing agent is isopropanol, and the soaking time is 30s.

[0126] Example 20

[0127] The present example provides a sand hardening process method of inorganic binder, which is different from example 13 in that the organic curing agent is acetonitrile, and the soaking time is 80s.

[0128] Example 21

[0129] The present example provides a sand hardening process method of inorganic binder, which is different from example 13 in that the organic curing agent is acetone, and the soaking time is 70s.

[0130] Example 22

[0131] The present example provides a sand hardening process method of inorganic binder, which comprises the following steps:

[0132] The Dalin scrubbing sand is laid on the 3D printing instrument, and then the binder and the organic curing agent are sprayed on the surface layer of the sand in turn, and 3D printing is formed; the foregoing process is repeated until the 3D printing is completed. The binder is a modulus of 2.0 sodium silicate for casting, and the organic curing agent is anhydrous ethanol. The mass ratio of the sand, the binder and the organic curing agent is 100:2:0.5.

[0133] The tensile strength of the sample is tested by a hydraulic testing machine, the average value of the sample is taken within 60s to measure the instantaneous strength; the final strength of the sample is tested after the sample is placed in the room for 24h. The results are shown in Table 1.

[0134] Example 23

[0135] The present example provides a sand hardening process method of inorganic binder, which is different from example 22 in that the binder is modified sodium silicate, and the organic curing agent is methanol.

[0136] Example 24

[0137] The present example provides a sand hardening process method of inorganic binder, which comprises the following steps:

[0138] The Dalin scrubbing sand and the binder are mixed, and then the mixture is laid on the 3D printing instrument, the organic curing agent is sprayed, and 3D scanning is formed; the foregoing process is repeated until the 3D printing is completed. The binder is a modulus of 2.0 sodium silicate for casting, and the organic curing agent is anhydrous n-propanol. The mass ratio of the sand, the binder and the organic curing agent is 100:2:0.5.

[0139] Example 25

[0140] This example provides a method for inorganic binder sand hardening process, which is different from example 24 in that the binder is modified water glass and the organic curing agent is isopropanol.

[0141] Example 26

[0142] This example provides a method for inorganic binder sand hardening process, which is different from example 22 in that 1% of hardening accelerator crystalline silica by weight is added to the Dalin scrubbing sand.

[0143] Example 27

[0144] This example provides a method for inorganic binder sand hardening process, which is different from example 23 in that 1% of hardening accelerator microsilica by weight is added to the Dalin scrubbing sand.

[0145] The existing sand core surface repair mostly uses water-based repair mud, as shown in Figure 2 , which needs to utilize the residual heat in the sand core forming and application process to achieve drying and molding effect. For the core at room temperature, especially the inorganic sand core with serious hygroscopic tendency, water-based repair mud is not suitable for surface repair, but will increase the probability of casting defects in the repaired part. Therefore, the effect of using mode four for inorganic binder sand surface repair and / or surface hardening is further investigated in the embodiments of the present application, as follows:

[0146] Example 28

[0147] This example provides a method for inorganic binder sand surface repair and surface hardening, which is aimed at the local loose part of inorganic binder sand with surface defects, as shown in Figure 1 A of FIG., obvious irregular pores and loose can be seen. These local loose parts are prone to produce sand inclusion, sand sticking, and casting defects such as protrusions in casting. The inorganic binder sand is prepared by the method of example 1, and the inorganic binder sand with surface defects is selected therefrom. The local repair process for the loose part is as follows:

[0148] Place the sand core on the workbench, heat the sand core surface temperature to 180℃, apply a layer of inorganic sand on the loose part, spray the organic curing agent methanol for hardening, the single spraying time is 2s, and repeat the spraying for 5 times. Detect the surface hardness of the sand core before and after treatment by using the sand mold hardness tester, parallel determination for 5 times, take the average value, and the surface structure of the treated sand core is shown in Figure 1 B of FIG. ; and after placing the sand core before and after treatment in the room for 24h, test the final strength of the sand core by using the hydraulic testing machine. The results are shown in Table 2 (examples 29-34 are the same).

[0149] Example 29

[0150] The present example provides a method for repairing and hardening the surface of inorganic binder sand. The inorganic binder sand is the same as in Example 28. The difference between the present example and Example 28 is that the sand core surface temperature is 120°C, the organic curing agent is ethanol, and the spraying frequency is 10 times.

[0151] Example 30

[0152] The present example provides a method for repairing and hardening the surface of inorganic binder sand. The inorganic binder sand is the same as in Example 28. The difference between the present example and Example 29 is that the spraying frequency is 1 time.

[0153] Example 31

[0154] The present example provides a method for repairing and hardening the surface of inorganic binder sand. The inorganic binder sand is the same as in Example 28. The difference between the present example and Example 29 is that the sand core surface temperature is 180°C and the spraying frequency is 5 times.

[0155] Example 32

[0156] The present example provides a method for repairing and hardening the surface of inorganic binder sand. The inorganic binder sand is the same as in Example 28. The difference between the present example and Example 28 is that the sand core surface temperature is 200°C, the organic curing agent is n-propanol, and the spraying frequency is 8 times.

[0157] Example 33

[0158] The present example provides a method for repairing and hardening the surface of inorganic binder sand. The inorganic binder sand is the same as in Example 28. The difference between the present example and Example 28 is that the sand core surface temperature is 250°C and the organic curing agent is acetone.

[0159] Example 34

[0160] The present example provides a method for repairing and hardening the surface of inorganic binder sand. The inorganic binder sand is the same as in Example 28. The difference between the present example and Example 28 is that the sand core surface temperature is 120°C, the organic curing agent is a mixture of methanol and ethanol in a volume ratio of 1:1, and the spraying frequency is 2 times.

[0161] Example 35

[0162] The present example provides a method for repairing and hardening the surface of inorganic binder sand. The inorganic binder sand is the same as in Example 28. The difference between the present example and Example 28 is that the sand core surface temperature is 20°C, the organic curing agent is acetonitrile, and the spraying frequency is 3 times.

[0163] Comparative Example 1

[0164] The present comparative example provides a method for hardening inorganic binder sand. The specific operation is as follows:

[0165] At 0.2 MPa, CO2 gas was blown into the inorganic binder sand core sample for 60 s, after the blowing, the CO2 gas pipeline was closed; then at 0.15 MPa, compressed air was blown into the inorganic binder sand core sample for 30 s, after the blowing, the sample was taken out, the tensile strength of the sample was detected by a hydraulic testing machine, the average value of the sample was taken within 60 s; after the sample was placed in the room for 24 h, the final strength of the sample was tested. The preparation process of the inorganic binder sand core sample was the same as that in Example 1.

[0166] Comparative Example 2

[0167] The present comparative example provides an inorganic binder sand hardening process method, and the specific operation is as follows:

[0168] At 0.2 MPa, CO2 gas was blown into the inorganic binder sand core sample for 60 s, after the blowing, the CO2 gas pipeline was closed; then at 0.15 MPa, compressed air was blown into the inorganic binder sand core sample for 30 s, after the blowing, the sample was taken out, the tensile strength of the sample was detected by a hydraulic testing machine, the average value of the sample was taken within 60 s; after the sample was placed in the room for 24 h, the final strength of the sample was tested. The preparation process of the inorganic binder sand core sample was the same as that in Example 1.

[0169] Table 1: Test results of inorganic binder sand core samples of Examples 1-27 and Comparative Examples 1-2 (average value of 5 samples)

[0170]

[0171]

[0172] Table 2: Test results of inorganic binder sand core samples of Examples 28-34

[0173]

[0174] The data in Table 1 show that the "8" sample prepared according to the casting industry standard has a high tensile strength by using the hardening method of Examples 1-27, among which, the immediate strength can generally reach more than 0.4 MPa, the highest can reach more than 1.3 MPa, the 24 h tensile strength can generally reach more than 0.7 MPa, the highest can reach more than 2.0 MPa, while the tensile strength of the sample obtained by the conventional hardening method in Comparative Examples 1 and 2 is poor.

[0175] The data in Table 2 show that the inorganic binder sand hardening process method of the present application is applied to the repair and hardening of sand molds and cores, whether at room temperature or at high temperature, a sand mold or core repair product with a surface hardness improved by more than 6.4%, an actual surface hardness of more than 80 degrees, and a 24 h tensile strength unchanged or even better can be obtained.

[0176] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A process for inorganic binder sand hardening characterized in that, The process comprises: forming inorganic binder sand by layer-by-layer 3D printing of raw sand, inorganic binder and organic curing agent, and simultaneously hardening the inorganic binder sand; The organic curing agent is at least one selected from the group consisting of methanol, ethanol, ethylene glycol, propanol, acetonitrile and acetone; The mass ratio of the raw sand, the inorganic binder and the organic curing agent is controlled to be 100:2~3:0.1~1.

0.

2. The process of claim 1, wherein, The forming inorganic binder sand by layer-by-layer 3D printing of raw sand, inorganic binder and organic curing agent, and simultaneously hardening the inorganic binder sand is performed by one of the following methods: Method 1), spreading raw sand on a 3D printing instrument, then spraying inorganic binder and organic curing agent on the surface of the raw sand in turn, repeating the foregoing process until the 3D printing is completed; Method 2), mixing raw sand and inorganic binder, then spreading the mixture on a 3D printing instrument, spraying organic curing agent, repeating the foregoing process until the 3D printing is completed.

3. The process of claim 2, wherein, The inorganic binder is water glass.

4. The process of claim 2, wherein, The inorganic binder is modified water glass.

5. The process of claim 2, wherein, The raw sand is added with a hardening accelerator, and the amount of the hardening accelerator added is 0~50% of the mass of the inorganic binder.

6. The process of claim 5, wherein, The hardening accelerator is at least one selected from the group consisting of bauxite, crystalline silica, non-crystalline silica and wollastonite powder.

7. The process of claim 5, wherein, The hardening accelerator is silica powder or microsilica powder.

8. The process of claim 5, wherein, The hardening accelerator is surface-modified silica.

9. The process of claim 5, wherein, The hardening accelerator is fumed silica.

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