WO2017152589A1 - Method for producing mould and core through curing sodium silicate sand for casting by blowing - Google Patents

Abstract

Disclosed is a method for producing moulds and cores through curing sodium silicate sand for casting by blowing. A sand mixture for producing moulds and cores is filled into a forming tool by a core shooter or manually and then is shaped, and the operations of blowing, curing and stripping are carried out. Gases are sequentially blown in the order of CO₂ and compressed gas; or gases are sequentially blown in the order of compressed gas-CO₂-compressed gas. The method can solve the problem of over-blowing in the method for blowing CO₂ into sodium silicate sand, so that the amount of added sodium silicate is small, the strength is high, the speed of mould core production is high, and the method can help to increase casting quality and improve working conditions.

Description

Forming and core method for casting water glass sand blow air hardening Technical field

The invention relates to the field of casting technology, and more particularly to a molding and core method for blowing softening of glass sand for casting water.

Background technique

At present, in the casting production, the resin self-hardening sand type and core technology are widely used, mainly including: furan resin self-hardening sand, alkaline phenolic resin self-hardening sand, urethane resin self-hardening sand, Bonny resin self-hardening sand; The core mainly includes: a cold core box resin sand core, a hot core box resin sand core and a resin coated sand core. Cold core box resin sand core needs to be hardened with amine gas, amine gas is toxic and irritating, it is flammable and explosive, and it has certain risks in production, transportation, storage and use; The core box resin sand core and the resin coated sand core, the mold needs to be heated to 180-300 ° C, high energy consumption, large smell and poor working environment. The above-mentioned core technology requires the use of synthetic organic resin as a binder. The synthetic resin production process is complicated and the cost is high, and the artificial synthetic resin releases a large amount of toxic and odorous gases during the core making and pouring, which pollutes the environment and harms. The workers are in good health.

The existing inorganic binder preparation and core are mainly CO ₂ hardening type and core process of casting water glass sand blowing. The CO ₂ hardening process of casting water glass sand is invented by the Czechs in 1948 and started in casting in 1952. Factory promotion and application. Now many foundries still used, but the casting sand blowing CO ₂ water glass hardened metal wick technology there is a problem in the application: too easy to blowing, casting high amount of water glass, sand, low mechanical properties of the core, to ensure that the water The glass sand type and core have sufficient process performance, and the amount of glass for casting water has to be increased. The amount of glass for casting water is as high as 4% to 8%, and the collapsibility is poor. With a reduction of 1% in the amount of glass for casting casting, 50% for castings, and 4% for casting water glass. The sand removal time for castings is 25% of the amount of casting water glass added to 6% of the castings. Improving the mechanical properties of water glass sand and reducing its addition amount are the pursuits of foundry workers for decades.

Summary of the invention

The object of the present invention is to provide a casting method for solving the problem of the prior art, the CO ₂ hardening process for casting water glass sand blowing, the easy over-blowing in the core process, the high amount of casting water glass, and the low mechanical properties of the sand core. The method of making and core-sealing with water glass sand.

In order to achieve the above object, the present invention adopts a technical solution as follows:

A molding and core method for casting water glass sand blow air hardening, molding, core sand mixture is filled into a mold by a core shooting machine or a manual method, and then blown, hardened, and demoulded; CO ₂ -compressed The blowing mode of the gas is sequentially blown; or the blowing of the compressed gas - CO ₂ - compressed gas is sequentially performed.

The CO ₂ gas is a CO ₂ -containing mixed gas or a pure CO ₂ gas; wherein the mixed gas has a CO ₂ content of 40-99%, and the rest is industrial nitrogen or dry air; this can be beneficial to ensure the type and core quality. Reduce the consumption of functional gas CO ₂ .

The compressed gas is compressed air and/or compressed nitrogen. Further, the compressed gas is compressed air or compressed nitrogen having a dew point of less than 5 ° C; the water carrying capacity of the compressed air body is increased, and the mechanical properties of the core and the core are improved.

The blowing is performed by first blowing CO ₂ , then blowing the compressed gas, blowing the gas into the cavity of the mold for blowing hardening, the CO ₂ blowing pressure is 0.05-0.6 Mpa, the blowing time is 3-200 s; blowing the compressed gas The pressure is 0.05-0.7Mpa, the blowing time is 10s-2400s, and the mold is released after the end of the blowing.

The blowing is performed by first blowing CO ₂ , then blowing the compressed gas, blowing the gas into the cavity of the mold for blowing hardening, the CO ₂ blowing pressure is 0.05-0.4 MPa, the blowing time is 10-60 s; blowing the compressed gas The pressure is 0.1-0.5Mpa, the blowing time is 20s-200s, and the mold is released after the end of the blowing.

Blowing said first plate by blowing compressed gas injection mold cavity, the first blow compressed gas blowing pressure is 0.01-0.4Mpa, blowing time 5-600s; followed by blowing CO _2, CO ₂ insufflation pressure It is 0.05-0.6Mpa, the blowing time is 3-200s; after the end of blowing CO ₂ gas, the compressed gas is blown again, the blowing pressure is 0.05-0.7Mpa, the blowing time is 10s-2400s, and the blowing is completed after the end of blowing.

The blowing is to blow the compressed gas into the mold cavity through the blowing plate, first blowing the compressed gas, the compressed gas pressure is 0.03-0.3Mpa, the blowing time is 5-120s; then the CO ₂ and CO ₂ blowing pressure are blown. It is 0.05-0.4Mpa, the blowing time is 10-60s; after the CO ₂ gas is blown, the compressed gas is blown again, the blowing pressure is 0.1-0.5Mpa, the blowing time is 20s-200s, and the blowing is completed after the end of blowing.

The blowing of the CO ₂ gas is performed by pulse blowing.

The core sand mixture is composed of the following mass percentages of raw materials: 1.2-5.0% of the cast water glass, 0.0-2.5% of the reinforcing agent, and the balance is the raw sand.

The core sand mixture is composed of the following mass percentages of raw materials: 1.5-3.0% for casting water glass, 0.0-1.5% for reinforcing agent, and the balance is raw sand.

The water for casting is a water glass for blowing CO ₂ method, water glass for ester hardening method, and water glass for VRH method. The modulus of the glass for casting water: 1.2-3.5, preferably the modulus: 1.5-2.5.

The reinforcing agent is silica fume, zirconium fumed silica, precipitated silica, fumed silica and fly ash, and a mixture of two or more of the above.

The raw sand is silica sand, spherical sand, zircon sand, forsterite sand, chromite ore for casting.

The type and core manufactured by the invention can be placed in the workshop for 24 hours and longer, and after being naturally dried, it can be combined and poured. It can also be dried in a surface drying oven and poured into the box on the same day.

The beneficial effects of the present invention are as follows with respect to the prior art:

The invention provides a molding and core method for blowing water glass sand by casting water, which can solve the problem of over-blowing of the water glass sand blowing CO ₂ method, and the water glass addition amount is reduced by more than 50%; the water glass sand mixture is added After the reinforcing agent, the mold core method of the casting water glass sand blowing and the core method and the water glass blowing CO ₂ method can improve the mechanical properties of the obtained type and core by more than 100%, and the sand core The sand type has good collapsibility, the casting is easy to remove sand, and the old sand can be recycled. Moreover, the amount of gas generated is low, the molding process and the core process are non-toxic and have no irritating odor, which can improve working conditions and contribute to environmental protection.

detailed description

The technical solutions of the present invention will be described clearly and completely in conjunction with the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

The embodiment of the invention provides a molding and core method for blowing water and glass sand of a casting water, and the raw sand, the casting water glass and the reinforcing agent are mixed by a sand mixer to form a core sand mixture, and then the molding, The core sand mixture is filled into the mold by a core shooting machine or a manual method, and the gas is blown into the mold cavity by blowing CO ₂ and then compressed by a gas hardening method, and the CO ₂ blowing pressure is 0.05-0.6 Mpa. The blowing time is 3-200s; the compressed gas pressure is 0.05-0.7Mpa, the blowing time is 10s-2400s, the small and core blowing time is taken as the lower limit, the large and the core are properly extended for the blowing time, and the blowing is completed after the blowing.

For the preparation method of the core and the core with high draft strength: the raw sand, the casting water glass and the reinforcing agent are mixed by the sand mixer to form the core sand mixture, and then the core sand mixture is passed through the core shooting machine or the manual method. The mold is filled and molded, and the compressed gas-CO ₂ -compressed gas is blown in sequence, and the compressed gas pressure is 0.01-0.4 MPa, the blowing time is 5-600 s, and the CO ₂ blowing pressure is 0.05-0.6. Mpa, blowing time 3-200s; post-combustion compressed gas pressure is 0.05-0.7Mpa, blowing time is 10s-2400s, small, core blowing time takes the lower limit, large, core properly prolongs blowing time, after blowing ends mold. This blowing method is blow-hardened, and the strength of the core and the core is high, which prevents deformation and damage of the core and the core when the mold is released.

Sand type, core placed in the room and then naturally dried; can also be quickly dried by hot air drying oven, microwave drying oven.

The compressed gas is industrial compressed air or industrial nitrogen. The compressed gas is dehumidified, and the blowing effect is better when the dew point is lower than 5 °C.

In the embodiment of the present invention, the molding and core sand mixture is composed of the following mass percentage of raw materials: 1.2-5.0% of the cast water glass and 0.0-2.5% of the amorphous silica, and the original sand balance. Preferably, the core sand mixture is composed of the following mass percentages of raw materials: 1.5-3.0% of cast water glass and 0.0-1.5% of amorphous silica, the balance of raw sand.

In the embodiment of the present invention, the CO ₂ used is diluted with industrial nitrogen and dry air, and contains CO ₂ 80%, CO ₂ 60%, CO ₂ 40% CO ₂ , nitrogen and air mixed gas, and contains CO _{2 .} A comparative example was made with 99.9% of industrial CO ₂ and gas.

In the embodiment of the invention, the raw sand is silica sand, spherical sand, zircon sand, chromite ore for casting. Foundry blowing CO ₂ water glass with water glass method, water glass ester cured process, the VRH water glass method.

The reinforcing agent is silica fume, zirconium fumed silica, precipitated silica, fumed silica and fly ash, and a mixture of two or more of the above.

As a preferred mode of the embodiment of the present invention, pulsed blowing is employed when blowing CO ₂ gas.

In the embodiment of the present invention, the specific method of molding the core sand mixture into the mold cavity by the core shooting machine is: using the cold core box core shooting machine and the supporting mold to make the core, and the core sand mixture is mixed. The core shot is injected into the mold cavity by a core shooter at a pressure of 0.4-0.7 Mpa.

In the embodiment of the present invention, the specific method of molding the core sand mixture by the manual method into the mold is: after the molding and the core sand mixture are mixed, the sand chamber is continuously flowed into the mold cavity, and the core sand is formed. When the amount of the mixture is sufficient and the excess of 2-5% is exceeded, the sand mixing is stopped, the vibrating table is started, the vibration is tightened for 15-30 s, and the mixture is manually scraped to remove the excess molding and the core sand mixture.

The high-efficiency molding and core method of the water glass sand blowing and hardening provided by the embodiment of the invention can solve the problem of over-blowing of the water glass sand blowing CO ₂ method, and the water glass addition amount is reduced by more than 50%, and the obtained sand type can be obtained at the same time. The core mechanical properties are significantly improved, the sand core and sand type have good collapsibility, the castings are easy to remove sand, and the old sand can be recycled. Compared with the resin core, the gas volume of the method of the invention is reduced by more than 90%, the pores and crack defects of the casting are less, the casting yield is high, the molding process, the core process are non-toxic and no irritating odor, and the working condition can be improved; the solid waste discharge Less quantity is conducive to environmental protection.

Example 1

Adopt MLWA1 sample mechanism core of Suzhou Mingzhi Technology Co., Ltd. Core mix ratio: 1000g of paddling water washing sand, ZS-2.9 modulus is 2.85 casting water glass 30g, zirconium fumed silica 3g, mixed with laboratory blade type sand mixer, the core sand mixture is filled with incident sand The cylinder, under 0.5Mpa, uses compressed air to inject the core sand mixture into the standard "8" type test mold cavity. The core box mold descends with the main cylinder, pushes the blow plate to the top of the mold, and the main cylinder rises. Press the blowing plate tightly; start the blowing valve, and blow the CO ₂ gas into the sand core cavity through the blowing plate at 0.15Mpa, pulse blowing: every pulse, blow for 3s, stop for 5s, pulse three times After the end of the blowing, immediately start the gas exchange valve, close the CO ₂ gas pipeline, and connect the compressed air to the blowing plate of the mold, and blow the compressed air into the sand core cavity at a pressure of 0.2Mpa to blow the compressed air time. 15s, after blowing, open the box to take the core, three sand cores per box, make four boxes of 12 sand cores, use hydraulic testing machine to test the tensile strength of the "8" type sample, and measure the instantaneous strength within 60s, take 3 The average value of the sample only; after the chamber was placed for 24 hours, the final strength of the test sample. After testing, the instantaneous tensile strength: 0.16Mpa, 0.14Mpa, 0.15Mpa. The average value of the three samples was 0.15 MPa; the tensile strength after 24 hours: 1.2 Map, 1.1 MPa, and 1.3 MPa. The average tensile strength of the three samples was taken to be 1.2 Mpa for 24 h.

Example 2

Adopt MLWA1 sample mechanism core of Suzhou Mingzhi Technology Co., Ltd. Core mix ratio: Dalin washed sand 1000g, ZS-2.5 modulus is 2.2 casting water glass 30g, silica fume 3g, mixed with laboratory blade type sand mixer, the core sand mixture is loaded into the incident sand tube, At 0.5Mpa, the core sand mixture is injected into the standard “8” sample test mold cavity with compressed air. The core box mold is lowered with the main cylinder, pushed into the blow plate to the top of the mold, and the main cylinder rises and will blow. The plate is pressed tightly; the blowing valve is opened, and the CO ₂ gas is blown into the sand core cavity through the blowing plate at 0.1 Mpa, and the blowing time is 15 s; after the blowing is completed, the gas exchange valve is immediately opened to close the CO ₂ gas. Pipe, the compressed air is connected to the blowing plate of the mold, and the compressed air is blown into the cavity of the sand core at a pressure of 0.4Mpa, and the compressed air is blown for 25s. After the blowing is finished, the core is opened and the box is three. Sand core, manufacturing four boxes of 12 sand cores, using hydraulic testing machine to test the tensile strength of "8" type samples, measuring the instantaneous strength within 60s; the rest of the samples were placed in 900W Galanz microwave oven, start the microwave oven, bake for 3min, test Its strength after drying. After testing, the instantaneous tensile strength: 0.18Mpa, 0.17Mpa, 0.19Mpa. The average value of the three values in the middle was 0.18 MPa; the tensile strength after 24 hours: 1.8 Map.

Example 3

Adopt MLWA1 sample mechanism core of Suzhou Mingzhi Technology Co., Ltd. Core mix ratio: Dalin scrub sand 1000g, ester curing casting glass HYT S-106: 20g, silica fume 2g, fly ash 2g mixed with laboratory blade type sand mixer, the core sand mixture is loaded In the incident sand cylinder, at 0.5Mpa, the core sand mixture is injected into the standard "8" type test mold cavity with compressed air. The core box mold descends with the main cylinder and is pushed into the blow plate to the top of the mold. Ascending, the blowing plate is pressed; the blowing valve is started, and the CO ₂ gas is blown into the sand core cavity through the blowing plate at 0.18 MPa, and the pulse is blown: each pulse, blowing for 3 s, stopping for 5 s, Pulse three times; immediately after the end of the blowing, start the gas exchange valve, close the CO ₂ gas pipeline, insert the compressed nitrogen into the blow plate of the mold, blow the compressed nitrogen into the sand core cavity under the pressure of 0.4Mpa, blow compression Nitrogen time 20s, after blowing, open the box to take the core, three sand cores per box, make four boxes of 12 sand cores, use hydraulic testing machine to test the tensile strength of the "8" type sample, and measure the instantaneous strength within 60s. Take the average of 5 samples; the rest of the sample is placed in a 101-1 type, 2000W electric blast drying oven, After baking at 120-150 ° C for 10 min, the tensile strength of the sample which was cooled to room temperature after drying was measured, and the average value of the three samples was taken. After testing, the instantaneous tensile strength: 0.19Mpa, 0.25Mpa, 0.22Mpa. The average value of the three samples was 0.22 MPa; the tensile strength after 24 hours: 1.7 MPa, 1.8 MPa, and 1.8 MPa. The average tensile strength of the three samples at 24 h was 1.77 MPa.

Example 4, Example 5, Example 6, and Example 7 The implementation method and Example 1 of Example 4, Example 5, Example 6, and Example 7 were different except that the amount of the original sand and the amount of the foundry water glass were different. Similarly, the conditions and results of Example 1, Example 2, Example 3, Example 4, Example 5, Example 6, and Example 7 are listed in Table 1 below.

Table 1

Example 8

Adopt MLWA1 sample mechanism core of Suzhou Mingzhi Technology Co., Ltd. Core mix ratio: 1000g of silica sand in the paddock, water glass HYT S-106 for ester curing, 20g, zirconium fumed silica 3g, mixed with a laboratory blade type sand mixer, and the core sand mixture is incident. The sand cylinder, under 0.5Mpa, uses compressed air to inject the core sand mixture into the standard "8" type test mold cavity. The core box mold descends with the main cylinder, pushes the blow plate to the top of the mold, and the main cylinder rises. The blowing plate is pressed; the blowing valve is opened, and the compressed air gas is blown into the sand core cavity through the blowing plate at 0.05 Mpa, and the blowing time is 8 s; then the CO ₂ gas is blown through the blowing plate. Into the sand core cavity, blowing pressure 0.15Mpa, pulse blowing: each pulse, blowing 3s, stop 5s, pulse three times; after blowing CO ₂ gas, immediately start the gas exchange valve, close the CO ₂ gas pipeline, The compressed air is connected to the blown plate of the mold, and the compressed air is blown into the cavity of the sand core at a pressure of 0.2 Mpa, and the compressed air is blown for 25 s. After the end of the blowing, the core is opened and the core is three cores per box. , manufacturing four boxes of 12 sand cores, using hydraulic testing machine to test the tensile strength of "8" type samples, 60s Instant strength test, three samples were averaged; indoor place after 24h, a final strength of the test sample, three specimens were averaged. After testing, the instantaneous tensile strength: 0.48Map, 0.45Mpa, 0.46Mpa. The average value of the three samples was 0.46 MPa; the tensile strength after 24 hours: 1.74 Map, 1.78 MPa, and 1.80 MPa. The average tensile strength of the three samples at 24 h was 1.77 MPa.

The compressed air was treated by a RD-1SW type, a refrigerating dryer, and the compressed air dew point was 2-4 ° C after the treatment.

Example 9 and Example 10 Example 11 The implementation methods of Example 9, Example 10, and Example 11 were the same as those of Example 8 except that the amount of the original sand and the amount of the foundry water glass were different. The implementation conditions and results are listed in the table. 2.

Table 2

Example 12

In this embodiment, the ratio of the core mixture is: 40Kg of padding sand, the water for casting curing is HYT S-106, 0.8Kg, silica fume 0.08Kg, fly ash 0.08Kg, and the raw materials are successively put into the sand mixer. The sand mixing machine used is the S206 bowl-shaped sand mixer of Qingdao Fangxin Machinery Equipment Factory. After mixing the raw materials used for the core making, the core sand mixture is obtained, and then the core sand mixture is filled into the core box by the artificial core making process for molding. Specifically, the core sand mixture is continuously flowed into the 37kg sand core box through the flowing sand tank, and the amount of the core sand mixture is sufficient and the mixing sand is stopped when 2-5% is exceeded, the vibrating table is started, the tapping is performed for 20s, and the vibrating table used is Xinan Casting Machine XNZ29 vibrating table, after hand-scraping, manually scrape the surface of the core, insert two blowing pipes into the center of the sand core, and blow the CO ₂ gas into the sand core cavity through the blowing pipe at 0.2Mpa, pulse Blowing: every pulse, blowing for 5s, stopping for 5s, pulse four times; immediately after blowing, immediately open the gas exchange valve, close the CO ₂ gas pipeline, connect the compressed air, and compress the air at 0.2Mpa air pressure. Blowing into the sand core cavity, blowing compressed air for 120s, in the crane Under help, open core box, sand core removed. The sand core is placed between the cores for 24 hours or longer, and after the water content is volatilized, the boxes can be poured and poured.

Take 1 kg of the sand mixture of Example 12, and use the equipment of Example 1, the sand sample method, and the air blowing hardening method to obtain 9 standard "8" samples, and measure the instantaneous tensile strength: 0.16 MPa, 0.15 MPa, 0.17. Mpa. The average value of the three samples was 0.16 MPa; the tensile strength after 24 hours: 1.3 MPa, 1.5 MPa, and 1.4 MPa. Take the average tensile strength of the three samples for 24h at 1.4Mpa.

Example 13

In this embodiment, the compressed air is freeze-dehumidified, and the dew point of the compressed air is 2-4 °C.

In this embodiment, the ratio of the molding mixture is: 100Kg of Fujian sea sand, HYT S-106 for casting curing, 2.0Kg, zirconium fumed silica 0.2Kg, fly ash 0.2Kg, and the raw materials are successively put into the sand mixer. In the middle, the sand mixer used is S20 bowl-shaped sand mixer, mixed for 30s, and the raw materials used in the modeling are mixed to obtain the molding sand mixture. The sand tank is filled with sand loading 190kg sand box, and the above ratio is mixed with 100Kg modeling sand. Material, fill in the sand loading 190kg sand box, start the vibrating table, tapping for 25s, the vibrating table used is the Xinan caster XNZ29 vibrating table, and the surface of the sand box is manually scraped after tapping. Using the utility model patent: 201620231051.x water glass sand blowing gas hardening instrument blowing hardening, the six blowing pipes are evenly distributed, inserted into the sand center, and the blowing procedure is set: the compressed air is blown into the sand cavity at 0.1Mpa Inside, the blowing time is 15s; at 0.4Mpa, the CO ₂ gas is blown into the sand core cavity through the blowing pipe, pulse blowing: every pulse, blowing for 6s, stopping for 6s, pulse 5 times; after blowing Immediately start the gas exchange valve, close the CO ₂ gas pipeline, connect the compressed air, blow the compressed air into the sand core cavity under the pressure of 0.56Mpa, blow the compressed air for 600s, and take off the mold with the assistance of the crane. Mold. The sand type is placed in the workshop for 24 hours or longer. After the water content is volatilized, it can be combined and poured.

Take 1 kg of the sand mixture of Example 13 and use the apparatus of Example 1 to prepare a sand sample method and blow air hardening method to prepare The standard "8" sample was 9 pieces, and the instantaneous tensile strength of 3 samples was measured immediately: 0.35 Map, 0.34 Mpa, 0.36 Mpa. The average value of the three samples was the immediate tensile strength of 0.35 MPa; the tensile strength after 24 hours: 1.7 Map, 1.6 MPa, and 1.8 MPa. The average tensile strength of the three samples was 1.7 MPa for 24 h.

Comparative example 1

Adopt MLWA1 sample mechanism core of Suzhou Mingzhi Technology Co., Ltd. Core mix ratio: Dalin washed silica sand 1000g, ZS-2.5, modulus is 2.4 water glass, 60g, mixed with laboratory blade type sand mixer, the core sand mixture is loaded into the incident sand tube, at 0.5Mpa The core sand mixture is injected into the standard "8" sample test mold with compressed air, the core box mold is lowered with the main cylinder, pushed into the blow plate to the top of the mold, the main cylinder is raised, and the blow plate is pressed; The blowing valve, at 0.2Mpa, blows the CO ₂ gas into the sand core cavity through the blowing plate, and the blowing time is 30s; after the blowing, the mold is opened, and three sand cores per box are used to make four boxes of 12 sands. For the core, the tensile strength of the "8" type specimen was measured by a hydraulic testing machine, and the average value of the three samples was taken. After testing, the immediate tensile strength of 5 samples: 0.16Map, 0.13Mpa, 0.16Mpa. The average value of the three samples was 0.15 Mpa of immediate tensile strength; the tensile strength after 24 hours: 0.50 Map, 0.54 Mpa, and 0.52 Mpa. The average tensile strength of the three samples at 24 h was 0.52 MPa.

Comparative example 2

Adopt MLWA1 sample mechanism core of Suzhou Mingzhi Technology Co., Ltd. Core mix ratio: Dalin washed silica sand 1000g, ZS-2.5, modulus is 2.4 water glass, 30g, mixed with laboratory blade type sand mixer, the core sand mixture is loaded into the incident sand tube, at 0.5Mpa The core sand mixture is injected into the standard "8" sample test mold with compressed air, the core box mold is lowered with the main cylinder, pushed into the blow plate to the top of the mold, the main cylinder is raised, and the blow plate is pressed; Blowing valve, at 0.2Mpa, blowing CO ₂ gas into the sand core cavity through the blowing plate, blowing time 15s; after blowing CO ₂ gas, immediately start the gas exchange valve, close the CO ₂ gas pipeline, will Compressed air is connected to the blown plate of the mold. Under the pressure of 0.4Mpa, the compressed air is blown into the cavity of the sand core, and the compressed air is blown for 30s. After the end of the blowing, the core is opened and the core is three shells per box. Four sets of 12 sand cores were made, the tensile strength of the "8" type specimen was measured by a hydraulic testing machine, and the instantaneous strength was measured within 60s; the remaining samples were placed in a 900W Galanz microwave oven, and the mold was started after the micro-blowing was started. Three sand cores, four boxes of 12 sand cores were produced, and the "8" type specimens were tested by hydraulic testing machine. Intensity, take the average of 3 samples. After testing, the instantaneous tensile strength of the three samples was measured by the instantaneous tensile strength: 0.14 Map, 0.18 Mpa, 0.16 Mpa. The average value of the three samples was 0.16Mpa; the tensile strength after 24h: 0.55Map, 0.54Mpa, 0.56Mpa. The average tensile strength of the three samples for 24 h was 0.55 MPa.

Comparative example 3

Adopt MLWA1 sample mechanism core of Suzhou Mingzhi Technology Co., Ltd. Core mix ratio: Dalin washed silica sand 1000g, ZS-2.5, modulus is 2.4 water glass, 20g, silica fume 3g, mixed with laboratory blade type sand mixer, the core sand mixture is loaded into the injection sand tube, At 0.5Mpa, the core sand mixture is injected into the standard "8" sample test mold with compressed air. The core box mold is lowered with the main cylinder, pushed into the blow plate to the top of the mold, the main cylinder is raised, and the blow plate is to be blown. Pressing; blowing the air valve, blowing CO ₂ gas into the sand core cavity through the blowing plate, blowing pressure 0.15Mpa, pulse blowing: each pulse, blowing 3s, stopping 5s, pulse three times; blowing CO after ₂ gas exchange valve immediately actuated, closing the CO ₂ gas duct, the compressed air blow mold plate access, air pressure at 0.2Mpa, compressed air into the sand core cavity, compressed air blowing time 25s After the end of the air blowing, open the core of the box, three sand cores per box, make four boxes of 12 sand cores, use the hydraulic testing machine to test the tensile strength of the "8" type sample, and measure the instantaneous strength within 60s; the remaining samples Placed indoors for 24h, use hydraulic testing machine to test the tensile strength of the "8" type sample, take the flatness of 5 samples Mean. After testing, the instantaneous tensile strength: measured the instantaneous tensile strength of 5 samples immediately measured tensile strength: 0.17Map, 0.14Mpa, 0.16Mpa. The average value of the three samples was 0.156 Mpa; the tensile strength after 24 hours: 1.7 Map, 1.6 Mpa, and 1.8 Mpa. The average tensile strength of the three samples was 1.7 MPa for 24 h.

Comparative example 4

The CO ₂ used in Comparative Example 4 was a mixed gas containing 80% CO ₂ diluted with industrial nitrogen. The compressed air is freeze-dehumidified and has a dew point of 2-4 °C.

Adopt MLWA1 sample mechanism core of Suzhou Mingzhi Technology Co., Ltd. Core mix ratio: Dalin washed silica sand 1000g, ZS-2.5, modulus is 2.4 water glass, 20g, silica fume 3g, mixed with laboratory blade type sand mixer, the core sand mixture is loaded into the injection sand tube, At 0.5Mpa, the core sand mixture is injected into the standard "8" sample test mold with compressed air. The core box mold is lowered with the main cylinder, pushed into the blow plate to the top of the mold, the main cylinder is raised, and the blow plate is to be blown. Pressurize; start the blow valve, start the blow valve, blow the compressed air gas into the sand core cavity through the blow plate at 0.05Mpa, blow time, 8s; then blow the CO ₂ gas through the blow plate Into the sand core cavity, blowing pressure 0.15Mpa, pulse blowing: each pulse, blowing 3s, stop 5s, pulse three times; after blowing CO ₂ gas, immediately start the gas exchange valve, close the CO ₂ gas pipeline, The compressed air is connected to the blowing plate of the mold, and the compressed air is blown into the cavity of the sand core at a pressure of 0.2 Mpa, and the compressed air is blown for 25 s. After the blowing is finished, the core is opened, and three cores per box are placed. , manufacturing four boxes of 12 sand cores, using hydraulic testing machine to test the tensile strength of "8" type samples, 60s internal measurement Time intensity; the rest of the sample was placed indoors for 24 hours, and the tensile strength of the "8" type sample was measured by a hydraulic testing machine, and the average value of the three samples was taken. Tested: The instantaneous tensile strength of 3 samples was measured: 0.35Map, 0.34Mpa, 0.36Mpa. The average value of the three samples was 0.35 MPa; the tensile strength after 24 hours: 1.70 Map, 1.62 MPa, and 1.83 MPa. The average tensile strength of the three samples at 24 h was 1.73 MPa. The mechanical properties of Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4 are shown in Table 3.

The CO ₂ used in Comparative Example 5 is a mixed gas containing 60% CO ₂ diluted with industrial nitrogen; the CO ₂ used in Comparative Example 6 is a mixed gas diluted with industrial nitrogen and containing 40% of CO ₂ ; other implementation conditions and comparative examples 4 is the same, the results of Comparative Example 5 and Comparative Example 6 are shown in Table 3.

table 3

While the preferred embodiment of the invention has been described, it will be understood that Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and the modifications and

It is apparent that those skilled in the art can make various modifications and variations to the invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and modifications of the invention

Claims (9)

1. A molding and core method for casting water glass sand blow air hardening, molding a core sand mixture into a mold by a core shooting machine or a manual method, and then blowing, hardening, and demoulding; The blowing mode of the CO ₂ -compressed gas is sequentially blown; or the blowing of the compressed gas -CO ₂ -compressed gas is sequentially performed.
2. The method according to claim 1, wherein the CO ₂ gas is a pure CO ₂ gas or a CO ₂ -containing mixed gas; wherein the CO ₂ -containing mixture is The CO ₂ content in the gas is 40-99%, and the rest is industrial nitrogen or dry air;

   The compressed gas is compressed air and/or compressed nitrogen.
3. The method and core method for blowing softening of a casting water glass sand according to claim 1 or 2, wherein the blowing is performed by first blowing CO ₂ and then blowing a compressed gas to blow the gas into the mold cavity. The air is hardened, the CO ₂ blowing pressure is 0.05-0.6 MPa, the blowing time is 3-200 s, the blowing compressed gas pressure is 0.05-0.7 MPa, the blowing time is 10 s - 2400 s, and the blowing is completed after the end of blowing.
4. The method and core method for blowing softening of a casting water glass sand according to claim 3, wherein the blowing is performed by first blowing CO ₂ and then blowing a compressed gas to blow the gas into the cavity of the mold. blowing hardening, CO ₂ insufflation pressure is 0.05-0.4Mpa, blowing time 10-60s; blowing the compressed gas pressure 0.1-0.5Mpa, blowing time of 20s-200s, after the conclusion of the blow mold.
5. The method and core method for blowing softening of a casting water glass sand according to claim 1 or 2, wherein the blowing is performed by blowing a compressed gas into the mold cavity through a blowing plate, and first blowing the compressed gas. The blowing pressure is 0.01-0.4Mpa, the blowing time is 5-600s; then the CO _{2 is} blown, the CO ₂ blowing pressure is 0.05-0.6Mpa, the blowing time is 3-200s; after the CO ₂ gas is blown, the compressed gas is blown again. The blowing pressure is 0.05-0.7Mpa, the blowing time is 10s-2400s, and the mold is released after the blowing.
6. The method and core method for blowing softening of a casting water glass sand according to claim 5, wherein the blowing is performed by blowing a compressed gas into the cavity of the mold through a blowing plate, first blowing the compressed gas, and compressing. The gas pressure is 0.03-0.3Mpa, the blowing time is 5-120s; then the CO _{2 is} blown, the CO ₂ blowing pressure is 0.05-0.4Mpa, and the blowing time is 10-60s; after the CO ₂ gas is blown, the compressed gas is blown again. The blowing pressure is 0.1-0.5Mpa, the blowing time is 20s-200s, and the mold is released after the blowing.
7. The method and core method for blowing softening of a casting water glass sand according to any one of claims 1 to 6, wherein the CO ₂ gas is blown by pulse blowing.
8. The method and core method for blowing softening of a casting water glass sand according to claim 1, wherein the molding core sand mixture is composed of the following mass percentage of raw materials: casting water glass 1.2-5.0%, reinforcing agent 0.0-2.5% and the balance is raw sand.
9. The method and core method for blowing softening of a casting water glass sand according to claim 1, wherein the molding core sand mixture is composed of the following mass percentage of raw materials: casting water glass 1.5-3.0 %, reinforcing agent 0.0-1.5% and the balance is raw sand.