Organic ester hardened sodium silicate-bonded sand composite core making process

Abstract

The invention relates to the field of casting, in particular to an organic ester hardened sodium silicate sand composite core making process, which is characterized in that the mass ratio of core sand to sodium silicate to organic ester in a liquid material for making a core by using organic ester hardened sodium silicate sand is 100: (1.5-2): (0.15-0.25); after sand filling of the liquid material is completed, a plurality of carbon dioxide channels are formed through pricking; and placing the core box in a carbon dioxide environment for 30-40 seconds, waiting for 2-3 minutes in an air environment, and overturning and drawing. According to the invention, the liquid material is prepared according to a proper proportion, so that the liquid material can be quickly overturned and drawn when being placed in a carbon dioxide environment in a film preparation process, and the quality of a hardened core film meets the requirements.

Description

Technical Field

[0001] The invention relates to the field of casting, in particular to an organic ester hardened water glass sand composite core making process. Background Art

[0002] The organic ester used in organic ester hardened water glass sand is a low-toxic, low-viscosity, uniformly composed organic liquid with less pollution to the environment, high sand strength, and significantly reduced amount of binder (water glass). It is increasingly widely used in the production of steel castings.

[0003] The hardening process of organic ester-hardened water glass sand includes three stages. In the first stage, the organic ester is hydrolyzed in an alkaline aqueous solution to produce organic acid or alcohol. In the second stage, the organic ester reacts with the water glass binder to increase the modulus of the water glass. When the viscosity of the water glass exceeds the critical value during the reaction, the molding sand loses fluidity and solidifies. In the third stage, the water glass further loses water and hardens.

[0004] Due to the hardening principle of organic ester-hardened water glass sand, during the production process, it takes 20-25 minutes from filling sand and making cores to flipping and demolding.

[0005] In the production of steel castings, for sand cores made on automated production lines, due to the process rhythm of the production line itself, the hardening time of organic ester-hardened water glass sand will not hinder the production progress. However, some sand cores are not suitable for making on automated production lines due to their shape, structure and other reasons, and can only be made manually. It takes about 20 minutes to wait from filling sand to building strength of the sand core to flipping and demolding, which restricts the production progress and reduces production efficiency.

[0006] The patent with the publication number of CN106466704A discloses an organic ester hardened water glass sand suitable for forsterite sand and a preparation method thereof, comprising water glass, a cosolvent, a soluble alkali, and an alkaline phenolic resin, wherein the components are added with water glass, a cosolvent, a soluble alkali, and an alkaline phenolic resin; in the process of preparing the water glass, an active resin is added to the water glass by adding a cosolvent and a soluble alkali. The preparation method of the organic ester hardened water glass sand suitable for forsterite sand comprises the following specific steps: water glass modification: heating the water glass, keeping it warm, adding a soluble alkali and a cosolvent, adding an alkaline phenolic resin, increasing the temperature, cooling to room temperature, and making modified water glass. The invention aims at the various characteristics of forsterite sand and water glass in the process of molding and core making, so that the binder system of the invention has the advantages of both organic binders and inorganic binders. The inorganic binder has a low cost and strong environmental protection, and is applied in the field of casting technology. However, the patent does not solve the problems of long demolding time and low production efficiency. The patent with publication number CN101885035A discloses a modified additive for water glass used in casting and the production process and use method of the additive. It is composed of styrene-acrylate emulsion, urea-formaldehyde resin, quaternary ammonium salt and water, and the mass fraction of each component is 40% to 65% styrene-acrylate emulsion, 0% to 10% urea-formaldehyde resin, 0.1% to 0.5% quaternary ammonium salt, and 25% to 55% water. By dry recycling of old water glass sand, the residual Na2O content is controlled within a certain range, and ultra-low modulus water glass and the modified additive are matched to extend the usable time of the molding sand mixed with all or part of the recycled sand, and the molding sand has excellent process performance, and the recycling rate of the old water glass sand can reach more than 85%. Moreover, the water glass modified additive of the present invention can be directly added to the water glass at room temperature and stirred evenly, without complicated heating-cooling process, which is convenient for operation at the molding site. It also does not solve the problem of long demoulding time and low production efficiency. Summary of the invention

[0007] The technical problem to be solved by the present invention is: how to solve the problem of long demoulding time and low production efficiency in the core making process mentioned in the background technology.

[0008] The technical scheme adopted by the present invention is: an organic ester hardened water glass sand composite core making process, in which the mass ratio of core sand, water glass and organic ester in the liquid material of the organic ester hardened water glass sand core making is 100: (1.5-2): (0.15-0.25); after the liquid material is filled with sand, a plurality of carbon dioxide channels are punched out; the core box is placed in a carbon dioxide environment for 30s-40s, and then the core box is turned over and demolded after waiting for 2-3min in an air environment.

[0009] The diameter of the carbon dioxide channel is 8-10 mm, and the depth of the carbon dioxide channel reaches the middle of the sand core.

[0010] The core sand is made of regenerated sand, and the residual sodium content is ≤0.3% and the micro powder content is ≤0.5% by mass percentage; the water glass is made of water glass with a modulus of 2.15 and a density of 1.39g / cm3; and the organic ester is a medium ester.

[0011] The ambient temperature of the organic ester hardened water glass sand composite core making process is ≤30°C.

[0012] The beneficial effects of the present invention are as follows: the present invention can quickly flip and demold when the liquid material is placed in a carbon dioxide environment during the film making process by configuring the liquid material in a suitable proportion, and the quality of the hardened core film meets the requirements. The present invention makes full use of the hardening mechanism of "blowing CO2 gas into sodium water glass sand, and the sodium water glass can quickly change from liquid to solid", greatly reduces the waiting time for manual core making of organic ester hardened water glass sand from filling sand to building strength of the sand core to flipping and demolding, and improves production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic top view of a core box in an embodiment of the present invention; Figure 2 yes Figure 1 AA direction schematic diagram; Figure 3 yes Figure 1 BB direction schematic diagram; Figure 4 is a schematic diagram of an embodiment of the present invention in which a movable block is placed in a core box and assembled; Among them, 1. outer frame, 2. left padding block, 3. front padding block, 4. middle padding block, 5. rear padding block, 6. right padding block. DETAILED DESCRIPTION

[0014] An organic ester hardened water glass sand composite core making process is carried out according to the following steps: Step 1: Check the core box status. The core box in this embodiment is as follows: Figure 1-3 As shown. The core box surface is clean and has no obvious scratches. The assembly marks of the loose blocks in the core box and the outer frame correspond to each other, and the joints of the loose blocks are flat without steps. Blow away the floating sand in the core box.

[0015] Step 2: spraying a mold release agent, which is a mold release agent of the prior art. Spray the mold release agent on the surface of the active block in the core box, spraying evenly without accumulation.

[0016] Step 3: Raw material selection: modulus 2.15, density 1.39g / cm 3 The water glass is made of medium ester, and the organic ester is made of regenerated sand. The residual sodium content is ≤0.3% and the micro powder content is ≤0.5% by mass percentage.

[0017] Step 4: Liquid material configuration: adjust the liquid material ratio of organic ester hardened water glass sand for manual core making. By mass, core sand: water glass: organic ester = 100: (1.5-2): (0.15-0.25); when mixing the sand, first add organic ester to the core sand and mix evenly, then add water glass and mix evenly (using a sand mixer).

[0018] Step 5: Start the sand mixer, take the first sand, and place the live blocks. Figure 4 As shown, add sand layer by layer into the core box and compact it, and bury the core bone into the core box when filling the sand.

[0019] Step 6. Use a wooden scraper to poke the core sand, especially the parts in the core box that are difficult to compact. After compaction, use the wooden scraper to scrape the surface of the core head flat.

[0020] Step 7: After the core head is scraped flat, a carbon dioxide ventilation channel is manually pierced. The depth of the ventilation channel can be to the middle of the sand core, with a diameter of φ10mm. There are multiple carbon dioxide ventilation channels, and the interval between adjacent carbon dioxide ventilation channels is 3-5cm (including horizontal and vertical).

[0021] Step 8. Insert the carbon dioxide blowing tube into the carbon dioxide ventilation channel. During the blowing process, check the sand core by hand. The blowing time is 30s to 40s. Wait for about 2 to 3 minutes, then flip the mold over.

[0022] Step 9. Turn over the core box and take off the outer frame and each loose block in the frame in turn. Use a wooden hammer to gently tap each loose block during the removal process to facilitate the smooth removal of the loose block without damaging the sand core.

[0023] Step 10: Finish the surface of the sand core after demoulding, and lift the qualified sand core to the core storage bottom plate for storage.

Claims

1. An organic ester hardened water glass sand composite core making process, characterized in that: The mass ratio of core sand, water glass and organic ester in the liquid material for making the core of organic ester hardened water glass sand is 100: (1.5-2): (0.15-0.25); after the liquid material is filled with sand, a plurality of carbon dioxide channels are punched; the core box is placed in a carbon dioxide environment for 30s-40s, and then the core box is turned over and demolded after waiting for 2-3min in an air environment.

2. The organic ester hardened water glass sand composite core making process according to claim 1, characterized in that: The diameter of the carbon dioxide channel is 8-10 mm, and the depth of the carbon dioxide channel reaches the middle of the sand core.

3. The organic ester hardened water glass sand composite core making process according to claim 1, characterized in that: The core sand is made of regenerated sand, and the residual sodium content is ≤0.3% and the micro powder content is ≤0.5% by mass percentage; the water glass has a modulus of 2.15 and a density of 1.39g / cm 3 of water glass; the organic ester is a medium ester.

4. The organic ester hardened water glass sand composite core making process according to claim 1, characterized in that: The ambient temperature of the organic ester hardened water glass sand composite core making process is ≤30°C.

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