A lost foam casting process for high-strength spindle box castings

Abstract

This invention provides a lost foam casting process for high-strength spindle box castings, comprising the following steps: mold making, coating, drying, molding, casting, secondary shot blasting, and stress relief tempering. The high-strength spindle box castings produced by this invention exhibit high strength and good surface stability. They also possess high hardness and good thermal stability. Furthermore, the core hole positions of the high-strength spindle box castings produced by this invention show no casting defects, and the surface has consistent gloss and uniform density. The fast-drying silica sol prepared by this invention contains functional groups such as organozirconium, organotin, and fluorinated esters, which can improve the fast-drying performance of the silica sol. These additives can alter the surface tension, viscosity, and curing speed of the silica sol, thereby affecting the drying speed and drying effect.

Description

Technical Field

[0001] This invention relates to the field of casting technology, and in particular to a lost foam casting process for high-strength spindle box castings. Background Technology

[0002] The spindle box is a crucial component of various machine tools, and its quality and dimensional accuracy determine the machine tool's operational stability and machining precision. Spindle box castings have complex structures, varying wall thicknesses, and require high technical expertise. Casting defects such as sand inclusions, cracks, shrinkage cavities, and shrinkage holes are not permitted inside the casting, especially in critical areas such as shaft holes, jaws, and guide rails.

[0003] Chinese Patent CN209407341U discloses a lost foam casting method for a spindle box. The lost foam casting method for the spindle box includes a first lost foam casting unit (1), a second lost foam casting unit (2), and a third lost foam casting unit (3). The first lost foam casting unit (1) and the third lost foam casting unit (3) can be connected to the front and rear of the second lost foam casting unit (2), respectively. The beneficial effects of this utility model are: when applying for casting a spindle box, the lost foam can be easily removed from the sand box. There is no burning of the lost foam during casting, which reduces the environmental pollution of casting. Since there are no burning residues or gases from the lost foam in the spindle box, the product quality of the spindle box is more stable.

[0004] Chinese Patent CN115502331A discloses a high-strength lost foam casting method. The method involves creating a lost foam model with a gating system based on product drawings using a mold; preparing a lost foam shell based on the model; heating the prepared lost foam shell in a firing kiln to 850-900℃ to burn off the lost foam and create a high-strength shell for precision casting; and pouring molten metal into the fired high-strength shell to produce the precision casting. This invention eliminates the most complex and unstable process of lost foam casting by employing a high-strength lost foam casting method, significantly shortening the shell-making time. The entire production process takes only 3 days. This has profound significance for improving the impact of lost foam casting on shell quality, increasing production efficiency, reducing production costs, and enhancing enterprise competitiveness.

[0005] Chinese Patent CN115351225A relates to the field of casting technology, and more specifically to a lost foam casting process. This invention prevents burns to operators during the separation of molding sand from the formed casting. A lost foam casting process includes the following steps: S1: Fabricating a lost foam mold, assembling the mold, and then drying it;

[0006] S2: After brushing and spraying refractory coating on the surface of the foam disappearing mold, it is dried again; S3: The dried foam disappearing mold is placed in the casting device, molding sand is poured in, the molding sand is vibrated and compacted, and the surface of the molding sand is scraped smooth after a certain period of time; S4: Molten metal is poured into the mold for casting, the foam disappearing mold disappears, and the molten metal takes its place; S5: After casting is completed, the molding sand and casting are quickly separated by the casting device; S6: After the casting is rapidly cooled, it is placed in water for quenching, and the metal casting is obtained after removal. The casting temperature in S4 is 1500℃ and the pressure is 0.04MPa. In S6, it is rapidly cooled to 1050~1100℃.

[0007] The spindle box castings produced in the existing publicly available technology have disadvantages such as low strength, low hardness, and poor surface stability, and casting defects are prone to occur at the core hole position of the spindle box. Summary of the Invention

[0008] Based on this, the present invention provides a lost foam casting process for high-strength spindle box castings. The high-strength spindle box castings produced by this process have high hardness, good thermal stability, no casting defects at the core hole position of the spindle box, consistent surface gloss, and uniform density.

[0009] The present invention is achieved through the following technical solution.

[0010] A lost foam casting process for high-strength spindle box castings includes the following steps: mold making, coating, drying, molding, casting, secondary shot blasting, and stress relief tempering.

[0011] In one embodiment, the coating thickness is 2-5 mm, and it is applied in 3 coats; the coating is prepared by mixing 50-70 parts bauxite, 15-30 parts mica, 3-8 parts quick-drying silica sol, 0.3-1.5 parts bentonite, 0.1-1 parts attapulgite clay, 0.05-0.5 parts sodium dodecylbenzenesulfonate, 0.05-0.5 parts tributyl phosphate, and 60-80 parts water.

[0012] In one embodiment, the drying operation steps are: drying at 30-40℃ for 1-2 hours, drying at 35-45℃ for 1-2 hours, drying at 40-50℃ for 1-2 hours, drying at 45-55℃ for 1-3 hours, and drying at 50-60℃ for 3-6 hours.

[0013] In one embodiment, the shape is such that the central hole of the spindle box is always at the bottom, and furan resin is pre-filled inside the mold.

[0014] In one embodiment, the casting temperature is 1480-1540℃, the casting pressure is controlled between -0.045 and -0.05 MPa, the molten iron level is controlled between 2 / 3 and 3 / 4 during the casting process, and the pressure is maintained for 5-15 minutes after casting is completed.

[0015] In one embodiment, the molten iron is composed of 20-30 parts of 18# medium-manganese type I pig iron, 40-60 parts of A3 coil steel, 5-10 parts of recycled material, and 0.1-0.5 parts of inoculant; the composition of the molten iron is C: 3.1-3.2%; Si: 1.7-1.9%; Mn: 0.9-1.1%; S: 0.06-0.08%; P: 0.02-0.04%; Cr: 0.005-0.015%.

[0016] In one embodiment, the stress-relieving tempering furnace is used at a temperature of 500-580℃ for 8-12 hours, then heating is stopped, and the furnace is cooled to 90-130℃. The furnace door is then opened halfway, and the temperature is lowered to 25-40℃ before the furnace is hoisted out for secondary shot blasting.

[0017] In one embodiment, the inoculant is one or more of silicon-strontium inoculant, silicon-zirconium inoculant, silicon-calcium inoculant, and rare earth inoculant.

[0018] In one embodiment, the method for preparing the fast-drying silica sol is as follows:

[0019] H1: By weight, put 100-200 parts of silica sol and 5-8 parts of 3-mercaptopropyltriethoxysilane into a stirred tank, stir at 40-50°C for 2-5 hours, and dry to remove moisture;

[0020] H2: Add 0.002-0.04 parts zirconium acrylate, 3-6 parts hexafluorobutyl acrylate, 0.001-0.05 parts methylallyltri-n-butyltin, 200-500 parts DMF, and ethylenediamine to the above-mentioned stirred tank and stir at 40-50°C for 2-5 hours. Then add 2-5 parts benzoyl peroxide and stir at 70-80°C for 30-70 minutes. Then distill off the DMF and add water to prepare a sol with a solid content of 20-30 wt%. Stir at room temperature for 100-150 minutes to obtain a fast-drying silica sol.

[0021] In one embodiment, the silica sol has a particle size range of 5-20 nm and a solid content of 15-30 wt%.

[0022] The reaction mechanism of the above-mentioned fast-drying silica sol is as follows: the hydroxyl groups of silica sol particles undergo a condensation reaction with 3-mercaptopropyltriethoxysilane to obtain a mercaptopropyl-containing silica sol; the mercaptopropyl-containing silica sol undergoes a mercapto addition reaction with zirconium acrylate, hexafluorobutyl acrylate, and methylallyltri-n-butyltin, respectively, and then polymerizes to obtain the fast-drying silica sol.

[0023] Compared with the prior art, the lost foam casting process for high-strength spindle box castings of the present invention has the following significant effects:

[0024] 1. The high-strength spindle box casting of this invention has high strength and good surface stability;

[0025] 2. The high-strength spindle box casting produced by this invention has high hardness and good thermal stability;

[0026] 3. The high-strength spindle box casting of the present invention has no casting defects at the core hole position of the spindle box, and the surface has a consistent gloss and uniform density.

[0027] 4. The functional groups such as organozirconium, organotin, and fluorinated esters in the fast-drying silica sol prepared by this invention can improve the fast-drying performance of the silica sol; these additives can change the surface tension, viscosity, curing speed, etc. of the silica sol, thereby affecting the drying speed and drying effect. Detailed Implementation

[0028] To facilitate understanding of the present invention, a more comprehensive description will be provided below. The invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] Example 1

[0031] A lost foam casting process for high-strength spindle box castings includes the following steps: mold making, coating, drying, molding, casting, secondary shot blasting, and stress relief tempering.

[0032] The coating is 2mm thick and is applied in 3 coats. The coating is prepared by mixing 50kg bauxite, 15kg mica, 3kg quick-drying silica sol, 0.3kg bentonite, 0.1kg attapulgite clay, 0.05kg sodium dodecylbenzenesulfonate, 0.05kg tributyl phosphate, and 60kg water.

[0033] The drying process is as follows: 1 hour at 30℃, 1 hour at 35℃, 1 hour at 40℃, 1 hour at 45℃, and 3 hours at 50℃.

[0034] The aforementioned design ensures that the central hole of the spindle box is always at the bottom, and furan resin is pre-filled inside the mold.

[0035] The casting temperature is 1480℃, the casting pressure is controlled at -0.045Mpa, the molten iron level is controlled at 2 / 3 during the casting process, and the pressure is held for 5 minutes after casting is completed.

[0036] The molten iron is composed of 20 kg of 18# medium-manganese pig iron, 40 kg of A3 coiled steel, 5 kg of recycled material, and 0.1 kg of inoculant; the composition of the molten iron is C: 3.1%; Si: 1.7%; Mn: 0.9%; S: 0.06%; P: 0.02%; Cr: 0.005%.

[0037] The stress-relief furnace used for tempering was heated to 500°C for 8 hours. After heating was stopped and the furnace was cooled to 90°C, the furnace door was opened halfway to allow the temperature to drop to 25°C. The furnace was then hoisted out of the furnace for secondary shot blasting.

[0038] The inoculant is a silicon-strontium inoculant.

[0039] The preparation method of the fast-drying silica sol is as follows:

[0040] H1: Place 100 kg of silica sol and 5 kg of 3-mercaptopropyltriethoxysilane into a stirred tank, stir at 40°C for 2 hours, and then dry to remove moisture;

[0041] H2: Add 0.002 kg zirconium acrylate, 3 kg hexafluorobutyl acrylate, 0.001 kg methylallyltri-n-butyltin, 200 kg DMF, and ethylenediamine to the above-mentioned stirred tank and stir at 40°C for 2 hours. Then add 2 kg benzoyl peroxide and stir at 70°C for 30 minutes. Then distill off the DMF and add water to prepare a sol with a solid content of 20 wt%. Stir at room temperature for 100 minutes to obtain a fast-drying silica sol.

[0042] The silica sol has a particle size range of 5 nm and a solid content of 15 wt%.

[0043] Example 2

[0044] A lost foam casting process for high-strength spindle box castings includes the following steps: mold making, coating, drying, molding, casting, secondary shot blasting, and stress relief tempering.

[0045] The coating is 3mm thick and is applied in 3 coats. The coating is prepared by mixing 55kg bauxite, 20kg mica, 4kg quick-drying silica sol, 0.8kg bentonite, 0.8kg attapulgite clay, 0.2kg sodium dodecylbenzenesulfonate, 0.2kg tributyl phosphate, and 65kg water.

[0046] The drying process is as follows: drying at 35℃ for 1.5 hours, drying at 40℃ for 1.5 hours, drying at 45℃ for 1.5 hours, drying at 50℃ for 2 hours, and drying at 55℃ for 4 hours.

[0047] The aforementioned design ensures that the central hole of the spindle box is always at the bottom, and furan resin is pre-filled inside the mold.

[0048] The casting temperature is 1500℃, the casting pressure is controlled at -0.045Mpa, the molten iron level is controlled at 2 / 3 during the casting process, and the pressure is held for 8 minutes after casting is completed.

[0049] The molten iron is composed of 24 kg of 18# medium-manganese pig iron, 45 kg of A3 coiled steel, 6 kg of recycled material, and 0.2 kg of inoculant; the composition of the molten iron is C: 3.1%; Si: 1.8%; Mn: 1.0%; S: 0.07%; P: 0.03%; Cr: 0.01%.

[0050] The stress-relief furnace used for tempering was heated to 530°C for 9 hours. After heating was stopped and the furnace was cooled to 100°C, the furnace door was opened halfway to allow the temperature to drop to 30°C. The furnace was then hoisted out of the furnace for secondary shot blasting.

[0051] The inoculant is a silicon-zirconium inoculant.

[0052] The preparation method of the fast-drying silica sol is as follows:

[0053] H1: Place 140 kg of silica sol and 6 kg of 3-mercaptopropyltriethoxysilane into a stirred tank, stir at 45°C for 3 hours, and then dry to remove moisture;

[0054] H2: Add 0.01 kg zirconium acrylate, 4 kg hexafluorobutyl acrylate, 0.02 kg methyl allyl tri-n-butyltin, 300 kg DMF, and ethylenediamine to the above-mentioned stirred tank and stir at 45°C for 3 hours. Then add 3 kg benzoyl peroxide and stir at 75°C for 40 minutes. Then distill off the DMF and add water to prepare a sol with a solid content of 25 wt%. Stir at room temperature for 110 minutes to obtain a fast-drying silica sol.

[0055] The silica sol has a particle size range of 10 nm and a solid content of 20 wt%.

[0056] Example 3

[0057] A lost foam casting process for high-strength spindle box castings includes the following steps: mold making, coating, drying, molding, casting, secondary shot blasting, and stress relief tempering.

[0058] The coating is 4mm thick and is applied in 3 coats. The coating is prepared by mixing 65kg bauxite, 25kg mica, 7kg quick-drying silica sol, 1.2kg bentonite, 0.8kg attapulgite clay, 0.4kg sodium dodecylbenzene sulfonate, 0.4kg tributyl phosphate, and 75kg water.

[0059] The drying process is as follows: drying at 35℃ for 1.5 hours, drying at 40℃ for 1.5 hours, drying at 45℃ for 1.5 hours, drying at 50℃ for 2 hours, and drying at 55℃ for 5 hours.

[0060] The aforementioned design ensures that the central hole of the spindle box is always at the bottom, and furan resin is pre-filled inside the mold.

[0061] The casting temperature is 1520℃, the casting pressure is controlled at -0.05Mpa, the molten iron level is controlled at 3 / 4 during the casting process, and the pressure is held for 13 minutes after casting is completed.

[0062] The molten iron is composed of 28 kg of 18# medium-manganese pig iron, 55 kg of A3 coil steel, 8 kg of recycled material, and 0.4 kg of inoculant; the composition of the molten iron is C: 3.2%; Si: 1.8%; Mn: 1%; S: 0.07%; P: 0.03%; Cr: 0.01%.

[0063] The stress-relief furnace used for tempering was heated to 560°C for 11 hours. After heating was stopped and the furnace was cooled to 120°C, the furnace door was opened halfway to allow the temperature to drop to 35°C. The furnace was then hoisted out of the furnace for secondary shot blasting.

[0064] The inoculant mentioned is a silicon-calcium inoculant.

[0065] The preparation method of the fast-drying silica sol is as follows:

[0066] H1: Place 180 kg of silica sol and 7 kg of 3-mercaptopropyltriethoxysilane into a stirred tank, stir at 45°C for 4 hours, and then dry to remove moisture;

[0067] H2: Add 0.03 kg zirconium acrylate, 5 kg hexafluorobutyl acrylate, 0.04 kg methylallyltri-n-butyltin, 400 kg DMF, and ethylenediamine to the above-mentioned stirred tank and stir at 405°C for 4 hours. Then add 4 kg benzoyl peroxide and stir at 75°C for 60 minutes. Then distill off the DMF and add water to prepare a sol with a solid content of 25 wt%. Stir at room temperature for 140 minutes to obtain a fast-drying silica sol.

[0068] The silica sol has a particle size range of 15 nm and a solid content of 25 wt%.

[0069] Example 4

[0070] A lost foam casting process for high-strength spindle box castings includes the following steps: mold making, coating, drying, molding, casting, secondary shot blasting, and stress relief tempering.

[0071] The coating is 5mm thick and is applied in 3 coats. The coating is prepared by mixing 70kg bauxite, 30kg mica, 8kg quick-drying silica sol, 1.5kg bentonite, 1kg attapulgite clay, 0.5kg sodium dodecylbenzenesulfonate, 0.5kg tributyl phosphate, and 80kg water.

[0072] The drying process is as follows: drying at 40℃ for 2 hours, drying at 45℃ for 2 hours, drying at 50℃ for 2 hours, drying at 55℃ for 3 hours, and drying at 60℃ for 6 hours.

[0073] The aforementioned design ensures that the central hole of the spindle box is always at the bottom, and furan resin is pre-filled inside the mold.

[0074] The casting temperature is 1540℃, the casting pressure is controlled at -0.05Mpa, the molten iron level is controlled at 3 / 4 during the casting process, and the pressure is held for 15 minutes after casting is completed.

[0075] The molten iron is composed of 30 kg of 18# medium-manganese pig iron, 60 kg of A3 coiled steel, 10 kg of recycled material, and 0.5 kg of inoculant; the composition of the molten iron is C: 3.2%; Si: 1.9%; Mn: 1.1%; S: 0.08%; P: 0.04%; Cr: 0.015%.

[0076] The stress-relief furnace used for tempering was heated to 580°C for 12 hours. After heating was stopped and the furnace was cooled to 130°C, the furnace door was opened halfway to allow the temperature to drop to 40°C. The furnace was then hoisted out of the furnace for secondary shot blasting.

[0077] The inoculant mentioned is a rare earth inoculant.

[0078] The preparation method of the fast-drying silica sol is as follows:

[0079] H1: Place 200 kg of silica sol and 8 kg of 3-mercaptopropyltriethoxysilane into a stirred tank, stir at 50°C for 5 hours, and then dry to remove moisture;

[0080] H2: Add 0.04 kg zirconium acrylate, 6 kg hexafluorobutyl acrylate, 0.05 kg methyl allyl tri-n-butyltin, 500 kg DMF, and ethylenediamine to the above-mentioned stirred tank and stir at 50°C for 5 hours. Then add 5 kg benzoyl peroxide and stir at 80°C for 70 minutes. Then distill off the DMF and add water to prepare a sol with a solid content of 30 wt%. Stir at room temperature for 150 minutes to obtain a fast-drying silica sol.

[0081] The silica sol has a particle size range of 20 nm and a solid content of 30 wt%.

[0082] Comparative Example 1

[0083] A lost foam casting process for high-strength spindle box castings includes the following steps: mold making, coating, drying, molding, casting, secondary shot blasting, and stress relief tempering.

[0084] The coating is 2mm thick and is applied in 3 coats. The coating is prepared by mixing 50kg bauxite, 15kg mica, 3kg quick-drying silica sol, 0.3kg bentonite, 0.1kg attapulgite clay, 0.05kg sodium dodecylbenzenesulfonate, 0.05kg tributyl phosphate, and 60kg water.

[0085] The drying process is as follows: 1 hour at 30℃, 1 hour at 35℃, 1 hour at 40℃, 1 hour at 45℃, and 3 hours at 50℃.

[0086] The aforementioned design ensures that the central hole of the spindle box is always at the bottom, and furan resin is pre-filled inside the mold.

[0087] The casting temperature is 1480℃, the casting pressure is controlled at -0.045Mpa, the molten iron level is controlled at 2 / 3 during the casting process, and the pressure is held for 5 minutes after casting is completed.

[0088] The molten iron is composed of 20 kg of 18# medium-manganese pig iron, 40 kg of A3 coiled steel, 5 kg of recycled material, and 0.1 kg of inoculant; the composition of the molten iron is C: 3.1%; Si: 1.7%; Mn: 0.9%; S: 0.06%; P: 0.02%; Cr: 0.005%.

[0089] The stress-relief furnace used for tempering was heated to 500°C for 8 hours. After heating was stopped and the furnace was cooled to 90°C, the furnace door was opened halfway to allow the temperature to drop to 25°C. The furnace was then hoisted out of the furnace for secondary shot blasting.

[0090] The inoculant is a silicon-strontium inoculant.

[0091] The preparation method of the fast-drying silica sol is as follows:

[0092] H1: Place 100 kg of silica sol into a mixing vessel, stir at 40°C for 2 hours, and then dry to remove moisture;

[0093] H2: Add 0.002 kg zirconium acrylate, 3 kg hexafluorobutyl acrylate, 0.001 kg methylallyltri-n-butyltin, 200 kg DMF, and ethylenediamine to the above-mentioned stirred tank and stir at 40°C for 2 hours. Then add 2 kg benzoyl peroxide and stir at 70°C for 30 minutes. Then distill off the DMF and add water to prepare a sol with a solid content of 20 wt%. Stir at room temperature for 100 minutes to obtain a fast-drying silica sol.

[0094] The silica sol has a particle size range of 5 nm and a solid content of 15 wt%.

[0095] Comparative Example 2

[0096] A lost foam casting process for high-strength spindle box castings includes the following steps: mold making, coating, drying, molding, casting, secondary shot blasting, and stress relief tempering.

[0097] The coating is 2mm thick and is applied in 3 coats. The coating is prepared by mixing 50kg bauxite, 15kg mica, 3kg quick-drying silica sol, 0.3kg bentonite, 0.1kg attapulgite clay, 0.05kg sodium dodecylbenzenesulfonate, 0.05kg tributyl phosphate, and 60kg water.

[0098] The drying process is as follows: 1 hour at 30℃, 1 hour at 35℃, 1 hour at 40℃, 1 hour at 45℃, and 3 hours at 50℃.

[0099] The aforementioned design ensures that the central hole of the spindle box is always at the bottom, and furan resin is pre-filled inside the mold.

[0100] The casting temperature is 1480℃, the casting pressure is controlled at -0.045Mpa, the molten iron level is controlled at 2 / 3 during the casting process, and the pressure is held for 5 minutes after casting is completed.

[0101] The molten iron is composed of 20 kg of 18# medium-manganese pig iron, 40 kg of A3 coiled steel, 5 kg of recycled material, and 0.1 kg of inoculant; the composition of the molten iron is C: 3.1%; Si: 1.7%; Mn: 0.9%; S: 0.06%; P: 0.02%; Cr: 0.005%.

[0102] The stress-relief furnace used for tempering was heated to 500°C for 8 hours. After heating was stopped and the furnace was cooled to 90°C, the furnace door was opened halfway to allow the temperature to drop to 25°C. The furnace was then hoisted out of the furnace for secondary shot blasting.

[0103] The inoculant is a silicon-strontium inoculant.

[0104] The preparation method of the fast-drying silica sol is as follows:

[0105] H1: Place 100 kg of silica sol and 5 kg of 3-mercaptopropyltriethoxysilane into a stirred tank, stir at 40°C for 2 hours, and then dry to remove moisture;

[0106] H2: Add 0.002 kg zirconium acrylate, 0.001 kg methylallyltri-n-butyltin, 200 kg DMF, and ethylenediamine to the above-mentioned stirred tank and stir at 40°C for 2 hours. Then add 2 kg benzoyl peroxide and stir at 70°C for 30 minutes. Then distill to remove DMF and add water to prepare a sol with a solid content of 20 wt%. Stir at room temperature for 100 minutes to obtain a fast-drying silica sol.

[0107] The silica sol has a particle size range of 5 nm and a solid content of 15 wt%.

[0108] Comparative Example 3

[0109] A lost foam casting process for high-strength spindle box castings includes the following steps: mold making, coating, drying, molding, casting, secondary shot blasting, and stress relief tempering.

[0110] The coating is 2mm thick and is applied in 3 coats. The coating is prepared by mixing 50kg bauxite, 15kg mica, 3kg quick-drying silica sol, 0.3kg bentonite, 0.1kg attapulgite clay, 0.05kg sodium dodecylbenzenesulfonate, 0.05kg tributyl phosphate, and 60kg water.

[0111] The drying process is as follows: 1 hour at 30℃, 1 hour at 35℃, 1 hour at 40℃, 1 hour at 45℃, and 3 hours at 50℃.

[0112] The aforementioned design ensures that the central hole of the spindle box is always at the bottom, and furan resin is pre-filled inside the mold.

[0113] The casting temperature is 1480℃, the casting pressure is controlled at -0.045Mpa, the molten iron level is controlled at 2 / 3 during the casting process, and the pressure is held for 5 minutes after casting is completed.

[0114] The molten iron is composed of 20 kg of 18# medium-manganese pig iron, 40 kg of A3 coiled steel, 5 kg of recycled material, and 0.1 kg of inoculant; the composition of the molten iron is C: 3.1%; Si: 1.7%; Mn: 0.9%; S: 0.06%; P: 0.02%; Cr: 0.005%.

[0115] The stress-relief furnace used for tempering was heated to 500°C for 8 hours. After heating was stopped and the furnace was cooled to 90°C, the furnace door was opened halfway to allow the temperature to drop to 25°C. The furnace was then hoisted out of the furnace for secondary shot blasting.

[0116] The inoculant is a silicon-strontium inoculant.

[0117] The preparation method of the fast-drying silica sol is as follows:

[0118] H1: Place 100 kg of silica sol and 5 kg of 3-mercaptopropyltriethoxysilane into a stirred tank, stir at 40°C for 2 hours, and then dry to remove moisture;

[0119] H2: Add 0.002 kg zirconium acrylate, 3 kg hexafluorobutyl acrylate, 200 kg DMF, and ethylenediamine to the above-mentioned stirred tank and stir at 40°C for 2 hours. Then add 2 kg benzoyl peroxide and stir at 70°C for 30 minutes. Then distill to remove DMF and add water to prepare a sol with a solid content of 20 wt%. Stir at room temperature for 100 minutes to obtain a fast-drying silica sol.

[0120] The silica sol has a particle size range of 5 nm and a solid content of 15 wt%.

[0121] The above embodiments and comparative test methods:

[0122] 1. The brushability of the coating was determined using an NDJ-3 rotary viscometer to measure the brushing index of the coating.

[0123] 2. Coating strength: First, apply the coating to the glass plate. After the coating dries, use a viscosity cup to drop sand onto the glass plate until the coating is broken and the glass plate is exposed. Finally, weigh the total mass of the dropped sand as a quantitative indicator to judge the surface strength of the coating.

[0124] 3. Hardness testing shall be performed in accordance with GB / T230.1—2004.

[0125] Test results:

[0126]

[0127]

[0128] By comparing the data from the above embodiments and comparative examples, the high-strength spindle box castings produced by the present invention exhibit high strength and high hardness; the high-strength spindle box castings produced by the present invention show no casting defects at the core hole position of the spindle box, have consistent surface gloss, and uniform density; and the fast-drying silica sol prepared by the present invention has good fast-drying performance.

Claims

1. A high-strength spindle box casting lost foam casting process, the operating steps are: molding, coating, drying, molding, casting, secondary shot blasting, tempering stress relief; The coating thickness is 2-5 mm, and the coating is sprayed three times; the coating is prepared by stirring 50-70 parts of bauxite, 15-30 parts of mica, 3-8 parts of quick-drying silica sol, 0.3-1.5 parts of bentonite, 0.1-1 part of attapulgite clay, 0.05-0.5 parts of sodium dodecyl benzene sulfonate, 0.05-0.5 parts of tributyl phosphate, and 60-80 parts of water; The preparation method of the quick-drying silica sol is: H1: 100-200 parts of silica sol and 5-8 parts of 3-mercaptopropyl triethoxysilane are put into a stirring kettle, stirred at 40-50℃ for 2-5 hours, and dried to remove water; H2: 0.002-0.04 parts of zirconium acrylate, 3-6 parts of hexafluorobutyl acrylate, 0.001-0.05 parts of methyl allyl tri-n-butyl tin, 200-500 parts of DMF, and ethylenediamine are added into the above stirring kettle, stirred at 40-50℃ for 2-5 hours, then 2-5 parts of benzoyl peroxide is added, stirred at 70-80℃ for 30-70 minutes, then distilled to remove DMF, and then water is added to prepare a sol with a solid content of 20-30wt%, stirred at room temperature for 100-150 minutes, to obtain a quick-drying silica sol.

2. A lost foam casting process for a high-strength mainshaft case casting according to claim 1, characterized in that: The drying operation steps are: 30-40℃ for 1-2 hours, 35-45℃ for 1-2 hours, 40-50℃ for 1-2 hours, 45-55℃ for 1-3 hours, and 50-60℃ for 3-6 hours.

3. A high strength spindle housing foundry process by lost foam casting process as claimed in claim 1 wherein: The molding is that the spindle box center hole is always at the bottom, and furan resin is filled in the mold in advance.

4. A lost foam casting process for a high-strength mainshaft case casting according to claim 1, characterized in that: The casting temperature is 1480-1540℃, the casting pressure is controlled at -0.045~-0.05Mpa, the molten iron liquid level is controlled at 2 / 3~3 / 4 during the casting process, and the pressure is maintained for 5-15min after the casting is completed.

5. A lost foam casting process for a high-strength spindle- housing casting according to claim 4, characterized in that: The molten iron is composed of 20-30 parts of 18# medium manganese pig iron, 40-60 parts of A3 steel, 5-10 parts of recycled material, and 0.1-0.5 parts of inoculant; the composition of the molten iron is C: 3.1-3.2%; Si: 1.7-1.9%; Mn: 0.9-1.1%; S: 0.06-0.08%; P: 0.02-0.04%; Cr: 0.005-0.015%. The tempering stress relief temperature is 500-580℃, the holding time is 8-12h, then the heating is stopped, the temperature is cooled to 90-130℃, then half of the furnace door is opened, the temperature is cooled to 25-40℃, the casting is lifted out of the furnace, and the secondary shot blasting is performed.

6. A high strength head casting process by lost foam casting as claimed in claim 1 wherein: The inoculant is one or more of silicon strontium inoculant, silicon zirconium inoculant, silicon calcium inoculant, and rare earth inoculant.

7. A high strength head casting process by lost foam casting as claimed in claim 5 wherein: The particle size of the silica sol is 5-20nm, and the solid content is 15-30wt%.

8. A high strength head casting process by lost foam casting as claimed in claim 1 wherein: ​

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