Preparation process of low alloy steel bucket tooth shell by using waste sand as raw material of easy disintegration clay sand

Abstract

This invention relates to the field of casting technology, specifically to a process for preparing easily collapsible clay sand and low-alloy steel bucket tooth shell molds using waste sand as raw material. The process is characterized by a formula comprising the following parts by weight: 90-110 parts recycled waste sand, 1-6 parts binder, 2-12 parts collapsing liquid, 0.2-2 parts thermal conductive agent, and 2-6 parts water. The binder is sodium-based bentonite, the collapsing liquid is a CH28 type aqueous solution, and the thermal conductive agent is magnesium peroxide. This invention is environmentally friendly, activating the effective binding capacity of bentonite, thus reducing the amount of bentonite added by 50%, while achieving 100% complete collapsibility of the low-alloy steel bucket tooth shell mold. It exhibits excellent collapsibility performance and achieves 95% recycling of waste sand, significantly reducing solid waste emissions and new sand consumption, saving new sand costs, and making a significant contribution to environmental and resource protection.

Description

Technical Field

[0001] This invention relates to the field of casting technology, specifically to a process for preparing bucket tooth shell molds using waste sand as raw material, easily collapsible clay sand, and low alloy steel. Background Technology

[0002] Low-alloy steel bucket teeth coated sand molding is labor-intensive and inefficient. Therefore, vertical molding lines have been introduced for casting. Current technologies commonly used in gray cast iron and non-ferrous metal casting, employing the most advanced horizontal molding lines and imported DIS sand molding lines and vertical molding lines, all use wet mold shells. These processes have high gasification rates and require the addition of 5-10% red coal powder in the shell molding process. Furthermore, this method is limited to gray iron and ductile iron casting. After casting, the red coal powder burns at high temperatures, releasing high levels of SO2 and other harmful substances. During sand mixing, molding, pouring, and sand removal cleaning, irritating odors and fumes pollute the working environment and increase sulfur dioxide levels. The most serious issue is that producing one ton of casting requires ≥ one ton of resin sand (equivalent to an additional cost of ≥ 1150 yuan). Moreover, the molding process of such production lines requires a pressure of 80-120 kg to produce shell molds with a strength of over 8 MPa, ensuring that the shell molds do not crack whether casting is box-type or boxless. After high-temperature casting, such shell molds are extremely hard and unbreakable, and can only be discharged as solid waste. Currently, the existing foundry industry's solid waste is transported out and dumped, which wastes resources and causes water pollution, soil compaction, and vegetation withering. In view of this, the applicant has conducted in-depth research, which led to this case. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide an environmentally friendly process for preparing easily collapsible clay sand and low-alloy steel bucket tooth shells, which can activate the effective binding of bentonite, thereby reducing the amount of bentonite added by 50%, and can promote 100% complete collapse of the low-alloy steel bucket tooth shell. The collapse effect is excellent, and 95% of the waste sand is recycled. This greatly reduces solid waste emissions and new sand consumption, saves the cost of new sand, and makes a significant contribution to the protection of the environment and resources.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: easily collapsible clay sand made from waste sand, comprising the following weight proportions: 90-110 parts recycled waste sand, 1-6 parts binder, 2-12 parts collapsible liquid, 0.2-2 parts thermal conductivity agent, and 2-6 parts water. The binder is sodium bentonite, the collapsible liquid is CH28 type aqueous solution, and the thermal conductivity agent is magnesium peroxide.

[0005] Furthermore, the CH28 type aqueous solution comprises the following components by weight: 50-70 parts ethyl acetate, 6-20 parts alkali metal oxide, 11-32 parts silane, 10-30 parts lithium hydroxystearate, and 7-13 parts sodium polyacrylate.

[0006] Furthermore, the alkali metal oxide is R2O.nSiO2.

[0007] Furthermore, the CH28 type aqueous solution is a CH28 type aqueous solution with a mass concentration of 70-85%.

[0008] Furthermore, the thermal conductivity of magnesium peroxide is 418 W / (mK).

[0009] Furthermore, the binder has sodium-based bentonite as its end group.

[0010] Furthermore, the recycled waste sand is waste foundry sand shell mold or waste surface sand.

[0011] The manufacturing process for low-alloy steel bucket tooth shells, using any of the above-mentioned easily collapsible clay sands made from waste sand, includes the following steps:

[0012] Step 1: Vibrate and screen the recycled waste sand to select recycled waste sand with dust content ≤6% and moisture content ≤5%.

[0013] Step 2: Put the recycled waste sand with dust content ≤6% and moisture content ≤5% into a mixer, add the binder and mix for 3-5 minutes, take it out to constant weight, and obtain clay sand.

[0014] Step 3: Add the collapsible liquid and heat-conducting agent to the clay sand in sequence, then mix and stir evenly to obtain easily collapsible clay sand;

[0015] Step 4: The well-mixed and stirred easily collapsible clay sand is transported to the bucket tooth molding machine for molding to obtain the low alloy steel bucket tooth shell shape of easily collapsible clay sand.

[0016] Furthermore, in step one, the recycled waste sand is vibrated and sieved to 70-140 mesh; in step two, the mixing speed of the mixer is set to 70-120 r / min; and in step four, the molding pressure of the bucket tooth molding machine is set to 100-120 kg.

[0017] Furthermore, in step one, the recycled waste sand is sequentially passed through a flat plate vibrating feeder and a grate vibrating feeder for vibrating screening, with the screening time being 10-20 minutes.

[0018] As described above, the present invention provides a process for preparing easily collapsible clay sand and low-alloy steel bucket tooth shell molds using waste sand as raw material. Through the development of CH28 aqueous solution, corresponding easily collapsible clay sand and low-alloy steel bucket tooth shell molds are prepared. This process is environmentally friendly, and with the use of vertical molding lines, the CH28 aqueous solution can play a corresponding binding role during the molding of the low-alloy steel bucket tooth shell mold. The low-alloy steel bucket tooth shell mold has good overall strength. When cast with molten steel at over 1600 degrees Celsius, the low-alloy steel bucket tooth shell mold hardens instantly upon heating. After casting and cooling, it... It can easily disintegrate the low-alloy steel bucket tooth shell. After more than a month of production practice, it has been proven that it can activate the effective bonding of bentonite, thereby reducing the amount of bentonite added by 50%, and can promote the complete disintegration of the low-alloy steel bucket tooth shell. The disintegration effect is excellent, and 95% of the waste sand can be recycled, which greatly reduces solid waste discharge and new sand consumption, saves new sand costs, and makes a significant contribution to the protection of the environment and resources. At the same time, the low-alloy steel bucket tooth shell has high density, and the low-alloy steel bucket tooth castings basically do not have flash, burrs, sand holes or air holes, which can reduce welding and grinding time. Detailed Implementation

[0019] The present invention will be further described below through specific embodiments.

[0020] The easily collapsible clay sand made from waste sand according to the present invention comprises the following formula in parts by weight: 90-110 parts recycled waste sand, 1-6 parts binder, 2-12 parts collapsible liquid, 0.2-2 parts thermal conductivity agent, and 2-6 parts water. The binder is sodium bentonite, the collapsible liquid is CH28 type aqueous solution, and the thermal conductivity agent is magnesium peroxide.

[0021] The CH28 aqueous solution comprises the following components by weight: 50-70 parts ethyl acetate, 6-20 parts alkali metal oxide, 11-32 parts silane, 10-30 parts lithium hydroxystearate, and 7-13 parts sodium polyacrylate.

[0022] Ethyl acetate (C4H8O2) mainly serves to disperse debris after high temperatures. The alkali metal oxide, R2O.nSiO2, mainly serves to resist oxidation. Silane, also known as (propynoxy)trimethylsilane, mainly serves to resist high temperatures before casting and combustion. Lithium hydroxystearate (C18H35LiO3) and sodium polyacrylate, abbreviated as PAAS or PAA-Na, both mainly contribute to good strength performance during molding and are environmentally friendly.

[0023] Preferably, the CH28 aqueous solution is a CH28 aqueous solution with a mass concentration of 70-85%. In addition, the proportion of the purified water can be adjusted according to the humidity of the recycled waste sand on site.

[0024] In addition, the thermal conductivity of the magnesium peroxide (MgO2) is 418 W / (mK), and its thermal conductivity temperature is low and it is easy to burn. The binder has sodium-based bentonite as the end group, which mainly plays a bonding role and has good environmental protection properties. The recycled waste sand is waste foundry sand shell or waste surface sand.

[0025] The manufacturing process for low-alloy steel bucket tooth shells, using any one of the above-mentioned easily collapsible clay sands as raw materials, includes the following steps:

[0026] Step 1: Vibrate and screen the recycled waste sand to select recycled waste sand with dust content ≤6% and moisture content ≤5%.

[0027] Step 2: Put the recycled waste sand with dust content ≤6% and moisture content ≤5% into a mixer, add the binder and mix for 3-5 minutes, take it out to constant weight, and obtain clay sand.

[0028] Step 3: Add the collapsible liquid and heat-conducting agent to the clay sand in sequence, then mix and stir evenly to obtain easily collapsible clay sand;

[0029] Step 4: The well-mixed and stirred easily collapsible clay sand is transported to the bucket tooth molding machine for molding to obtain the low alloy steel bucket tooth shell shape of easily collapsible clay sand.

[0030] In step one, the recycled waste sand is vibrated and sieved to 70-140 mesh. In step two, the mixing speed of the mixer is set to 70-120 r / min. In step four, the molding pressure of the bucket tooth molding machine is set to 100-120 kg.

[0031] In step one, the recycled waste sand is passed through a flat plate vibrating feeder and a grate vibrating feeder in sequence for 10-20 minutes for vibrating screening.

[0032] Example 1

[0033] The easily collapsible clay sand made from waste sand includes the following formula in parts by weight: 100 parts waste foundry sand shell, 2 parts sodium-based bentonite with end base, 4 parts CH28 aqueous solution, 0.2 parts magnesium peroxide, and 6 parts water.

[0034] The CH28 aqueous solution is a CH28 aqueous solution with a mass concentration of 70%.

[0035] The manufacturing process of low-alloy steel bucket tooth shell includes the following steps:

[0036] Step 1: Vibrate and sieve the recycled waste sand to 70-140 mesh for 15 minutes, and screen out the recycled waste sand with dust content ≤3% and moisture content ≤5%.

[0037] Step 2: Place the recycled waste sand with a dust content of ≤3% and a moisture content of ≤5% into a mixer with a mixing speed of 100r / min, add the binder and mix for 3 minutes, then remove it to constant weight to obtain clay sand.

[0038] Step 3: Add CH28 type aqueous solution and magnesium peroxide to the clay sand in sequence, then mix and stir evenly to obtain easily collapsible clay sand;

[0039] Step 4: The well-mixed and stirred easily collapsible clay sand is transported to a bucket tooth molding machine with a molding pressure of 120 kg for molding to obtain a low alloy steel bucket tooth shell shape of easily collapsible clay sand.

[0040] Example 2

[0041] The easily collapsible clay sand made from waste sand comprises the following proportions by weight: 100 parts waste surface sand, 6 parts sodium-based bentonite with end base, 6 parts CH28 type aqueous solution, 2 parts magnesium peroxide, and 3 parts water.

[0042] The CH28 aqueous solution is a CH28 aqueous solution with a mass concentration of 80%.

[0043] The manufacturing process of low-alloy steel bucket tooth shell includes the following steps:

[0044] Step 1: Vibrate and sieve the recycled waste sand to 70-140 mesh for 15 minutes, and screen out the recycled waste sand with dust content ≤5% and moisture content ≤5%.

[0045] Step 2: Place the recycled waste sand with a dust content of ≤5% and a moisture content of ≤5% into a mixer with a mixing speed of 90r / min, add the binder and mix for 4min, take it out to constant weight, and obtain clay sand.

[0046] Step 3: Add CH28 type aqueous solution and magnesium peroxide to the clay sand in sequence, then mix and stir evenly to obtain easily collapsible clay sand;

[0047] Step 4: The well-mixed and stirred easily collapsible clay sand is transported to a bucket tooth molding machine with a molding pressure of 110 kg for molding to obtain a low alloy steel bucket tooth shell shape of easily collapsible clay sand.

[0048] Example 3

[0049] The easily collapsible clay sand made from waste sand includes the following formula in parts by weight: 100 parts of waste foundry sand shell, 4 parts of sodium-based bentonite with end base, 8 parts of CH28 type aqueous solution, 1 part of magnesium peroxide, and 4 parts of water.

[0050] The CH28 aqueous solution is a CH28 aqueous solution with a mass concentration of 85%.

[0051] The manufacturing process of low-alloy steel bucket tooth shell includes the following steps:

[0052] Step 1: Vibrate and sieve the recycled waste sand to 70-140 mesh for 15 minutes, and screen out the recycled waste sand with dust content ≤5% and moisture content ≤5%.

[0053] Step 2: Place the recycled waste sand with a dust content of ≤5% and a moisture content of ≤5% into a mixer with a mixing speed of 110r / min, add the binder and mix for 4 minutes, then remove it to constant weight to obtain clay sand.

[0054] Step 3: Add CH28 type aqueous solution and magnesium peroxide to the clay sand in sequence, then mix and stir evenly to obtain easily collapsible clay sand;

[0055] Step 4: The well-mixed and stirred easily collapsible clay sand is transported to a bucket tooth molding machine with a molding pressure of 110 kg for molding to obtain a low alloy steel bucket tooth shell shape of easily collapsible clay sand.

[0056] The low-alloy steel bucket tooth shell mold made of easily collapsible clay sand obtained above was tested and obtained the following performance parameters: the surface hardness of the low-alloy steel bucket tooth shell mold is 8.3-9.0 MPa, the cavity strength is 8.7-9.3 MPa, the overall strength of the low-alloy steel bucket tooth shell mold is good, the surface finish is good, and it meets the casting requirements. The casting temperature of the molten steel is 1637-1660℃. Its casting permeability is good and it is environmentally friendly. After being vibrated and screened, the sand removal rate of the low-alloy steel bucket tooth shell mold is 95-98%. The waste sand can be recycled and remolded, and the casting is complete and has an excellent appearance.

[0057] Through the development of CH28 aqueous solution, corresponding easily collapsible clay sand and low-alloy steel bucket tooth shell molds were prepared. These solutions are environmentally friendly and, when used with vertical molding lines, provide a binding effect during the molding of the low-alloy steel bucket tooth shell molds. The low-alloy steel bucket tooth shell molds exhibit good overall strength. When cast with molten steel at over 1600 degrees Celsius, the molds harden instantly upon heating. However, after casting and cooling, the molds easily collapse. After a period of time... Months of production practice have proven that it can activate the effective bonding of bentonite, thereby reducing the amount of bentonite added by 50%, and can also promote the complete collapse of the low alloy steel bucket tooth shell mold by 100%, with excellent collapse effect and 95% waste sand recycling, which greatly reduces solid waste discharge and new sand consumption, saves new sand costs, and makes a significant contribution to the protection of the environment and resources. At the same time, the low alloy steel bucket tooth shell mold has high density, and the low alloy steel bucket tooth castings basically do not have flash, burrs, sand holes or air holes, which can reduce welding and grinding time.

[0058] The above are merely some specific embodiments of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention using this concept shall be considered as infringing upon the protection scope of the present invention.

Claims

1. A readily collapsible clay sand using waste sand as a raw material, characterized in that: The formula comprises the following parts by weight: 90-110 parts recycled waste sand, 1-6 parts binder, 2-12 parts collapsible liquid, 0.2-2 parts thermal conductivity agent, and 2-6 parts water. The binder is sodium bentonite, the collapsible liquid is a CH28 type aqueous solution, and the thermal conductivity agent is magnesium peroxide. The CH28 type aqueous solution comprises the following parts by weight: 50-70 parts ethyl acetate, 6-20 parts R2O.nSiO2, 11-32 parts silane, 10-30 parts lithium hydroxystearate, and 7-13 parts sodium polyacrylate. R2O is an alkali metal oxide, and the CH28 type aqueous solution has a mass concentration of 70-85%. ​ 2. The easily collapsible clay sand using waste sand as raw material according to claim 1, characterized in that: The thermal conductivity of the magnesium peroxide is 418 W / (mK).

3. The easily collapsible clay sand using waste sand as raw material according to claim 1, characterized in that: The recycled waste sand is waste foundry sand shell or waste surface sand.

4. A manufacturing process for low-alloy steel bucket tooth shells, characterized in that: The preparation of easily collapsible clay sand using waste sand as raw material as described in any one of claims 1-3 includes the following steps: Step 1: Vibrate and screen the recycled waste sand to select recycled waste sand with dust content ≤6% and moisture content ≤5%. Step 2: Put the recycled waste sand with dust content ≤6% and moisture content ≤5% into a mixer, add the binder and mix for 3-5 minutes, take it out to constant weight, and obtain clay sand. Step 3: Add the collapsible liquid and heat-conducting agent to the clay sand in sequence, then mix and stir evenly to obtain easily collapsible clay sand; Step 4: The well-mixed and stirred easily collapsible clay sand is transported to the bucket tooth molding machine for molding to obtain the low alloy steel bucket tooth shell shape of easily collapsible clay sand.

5. The manufacturing process of the low-alloy steel bucket tooth shell according to claim 4, characterized in that: In step one, the recycled waste sand is vibrated and sieved to 70-140 mesh. In step two, the mixing speed of the mixer is set to 70-120 r / min. In step four, the molding pressure of the bucket tooth molding machine is set to 100-120 kg.

6. The manufacturing process of the low-alloy steel bucket tooth shell according to claim 4, characterized in that: In step one, the recycled waste sand is passed through a flat plate vibrating feeder and a grate vibrating feeder in sequence for 10-20 minutes for vibrating screening.