CN115069980A - Method for preparing investment casting shell by using wax removal plug and ceramic plug and application thereof - Google Patents
Method for preparing investment casting shell by using wax removal plug and ceramic plug and application thereof Download PDFInfo
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- CN115069980A CN115069980A CN202210750790.XA CN202210750790A CN115069980A CN 115069980 A CN115069980 A CN 115069980A CN 202210750790 A CN202210750790 A CN 202210750790A CN 115069980 A CN115069980 A CN 115069980A
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- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims description 32
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- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 claims description 5
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Images
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/02—Sand moulds or like moulds for shaped castings
- B22C9/04—Use of lost patterns
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/12—Treating moulds or cores, e.g. drying, hardening
Abstract
The invention relates to the technical field of investment casting, in particular to a method for preparing an investment casting shell by utilizing a wax removal plug and a ceramic plug and application thereof. The method comprises the following steps: after the wax removing plug is connected with the wax mould module, coating paint on the surface of the wax removing plug and sanding to obtain a shell; sequentially dewaxing and roasting the shell to obtain a roasted shell; the wax removal plug is mainly prepared by pressing wax, and the shape of the wax removal plug comprises a cylinder and/or a round table; pressing and roasting the ceramic block; the ceramic plug is mainly prepared by pressing a first refractory material and wax, and the shape of the ceramic plug comprises a circular truncated cone; placing the ceramic plug into a wax discharge port of a roasting shell, then coating refractory mortar on the surfaces of the ceramic plug and the wax discharge port, and obtaining an investment casting shell after the refractory mortar is hardened; the refractory mortar is mainly composed of the second refractory material and the binder. The wax liquid can flow out in time by arranging the wax discharging plug; the ceramic plug is adopted to plug the wax discharge port, and refractory mortar is matched, so that foreign matters can be prevented from entering the shell.
Description
Technical Field
The invention relates to the technical field of investment casting, in particular to a method for preparing an investment casting shell by using a wax removal plug and a ceramic plug and application thereof, and more particularly relates to a method for preparing an investment casting shell by using a wax removal plug and a ceramic plug and a preparation method of an investment casting.
Background
Turbine guide, nozzle position temperature-bearing parts and turbine blades in the aviation and aerospace fields are generally formed by a high-temperature alloy investment casting method, the parts are complex in structure, and the casting difficulty is very high. In order to ensure the mold filling and feeding conditions of the casting, a pouring system is very complex, a wax mold is difficult to melt and flow out, and the dewaxed shell is easy to have the problems of wax residue, shell spalling and the like.
In order to ensure thorough dewaxing, a wax discharge port is required to be arranged at the position where the shell is unsmooth in wax discharge, and the wax discharge port is blocked after dewaxing and roasting. The method adopted at present is that a drill is used for drilling before dewaxing or a cylindrical wax rod with the length of about 20mm and the diameter of 3-10 mm is installed during wax mould assembling, the cylindrical wax rod is cut off or broken off during dewaxing, and the cylindrical wax rod is blocked by using a coating after roasting. However, when the coating is used for plugging, the problem that the coating is plugged into the inside of the wax discharge port or directly falls into the inside of the shell is easily caused, so that the castings are mixed and scrapped.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
The first purpose of the invention is to provide a method for preparing an investment casting shell by utilizing a wax removal plug and a ceramic plug, wherein wax liquid can flow out in time by arranging the wax removal plug; the ceramic plug is adopted to plug the wax discharge port, and refractory mortar is matched, so that foreign matters can be prevented from entering the shell. Solves the problems of unsmooth de-waxing, easy generation of shell spalling and casting inclusion caused by paint falling into the shell.
The second purpose of the invention is to provide a preparation method of the investment casting.
In order to achieve the above purpose of the present invention, the following technical solutions are adopted:
the invention provides a method for preparing an investment casting shell by using a wax removal plug and a ceramic plug, which comprises the following steps:
(a) after the wax removal plug is connected with the wax pattern module, coating paint (slurry) on the surface (namely the surface of the connected wax removal plug and the wax pattern module) and sanding to obtain a shell; and then sequentially dewaxing and roasting the shell to obtain a roasted shell.
In some specific embodiments of the present invention, the number of the wax discharging plugs can adopt any conventional number, and can also be set according to actual needs, and preferably the number of the wax discharging plugs is greater than or equal to 1, including but not limited to any one of the point values of 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 17, 18, 20, 24, 26, and 30 or any range value between any two.
In the step (a), the wax removal plug is mainly made of wax through pressing, and the shape of the wax removal plug comprises a cylinder and/or a circular truncated cone.
In some embodiments of the present invention, the shape of the wax discharging plug may be a cylinder, a circular truncated cone, or a combination (combination) of a cylinder and a circular truncated cone. Preferably, the wax discharging plug is in the shape of a combination of a cylinder and a circular truncated cone, as shown in fig. 1 and 2. Wherein the diameter of the bottom surface (upper bottom surface or lower bottom surface) of the cylinder is larger than the diameter of the bottom surface with larger diameter in the circular truncated cone.
In some embodiments, before the shell is dewaxed, the wax removing plug is cut at an end portion away from the wax pattern module to prepare for the subsequent dewaxing, so as to solve the problem of unsmooth wax removal. Preferably, the end of the wax removing plug far away from one end of the wax pattern module is in the shape of a cylinder, and after the cutting, the height of the cylinder is not more than 2mm (including but not limited to the point value of any one of 2mm, 1.9mm, 1.8mm, 1.6mm, 1.5mm, 1.3mm, 1.1mm, 1.0mm, 0.8mm, 0.5mm and 0.3mm or the range value between any two), more preferably 1-2 mm. Preferably, the cutting is performed in a direction parallel to the bottom surface (upper bottom surface or lower bottom surface) of the cylinder. More preferably, the cutting is performed using an angle grinder or a hacksaw blade.
In some specific embodiments of the invention, the dewaxing is performed using an electrically heated steam dewaxing kettle, wherein the pressure is from 0.6 to 0.9MPa (including but not limited to any one of 0.65MPa, 0.7MPa, 0.8MPa, 0.85MPa or any value in the range therebetween) and the dewaxing time is from 10 to 20min (including but not limited to any one of 11min, 13min, 15min, 18min, 19min or any value in the range therebetween).
In some specific embodiments of the present invention, in the step (a), the temperature of the roasting is 800 to 1000 ℃, including but not limited to any one of 820 ℃, 850 ℃, 880 ℃, 900 ℃, 910 ℃, 920 ℃, 940 ℃, 950 ℃, 970 ℃, 990 ℃ or a range between any two thereof; in the step (a), the roasting heat preservation time is 2-4 h, including but not limited to any one of 2.5h, 3h and 3.5h or any range value between any two. Preferably, the firing in step (a) is performed using a muffle furnace. Wherein the muffle comprises a slide-hearth muffle.
In some embodiments of the invention, in step (a), after the firing, the openings are cleaned of flash and burrs, and the cavity is blown of dust by compressed air.
In some embodiments of the present invention, in step (a), the coating material may be any conventional slurry that is commercially available. Preferably, the coating is mainly prepared from silica sol and at least one of zircon powder, corundum powder and mullite powder.
In some embodiments of the present invention, in step (a), the sand used for the sanding may be any commercially available sand that is conventional. For example, corundum and mullite.
(b) Pressing the ceramic plug, and roasting it.
In the step (b), the ceramic plug is mainly prepared by pressing a first refractory material and wax, and the shape of the ceramic plug comprises a truncated cone, as shown in fig. 3.
In some embodiments of the present invention, the cross-section of the ceramic plug shaped as a truncated cone comprises two rounded corners, i.e. the junction of the first bottom surface and the side surface of the ceramic plug has a certain curvature, as shown in fig. 4, which facilitates the placement of the ceramic plug into the wax discharge opening of the fired shell.
In some specific embodiments of the present invention, the step (a) and the step (b) are not in sequence, and may be performed first, or simultaneously.
(c) And (5) putting the ceramic plug obtained in the step (b) into the wax discharge port of the roasting shell obtained in the step (a), wherein the wax discharge port is a hole structure (cavity structure) formed by the wax discharge plug after dewaxing, then coating refractory mortar on the surfaces of the ceramic plug and the wax discharge port, and obtaining the investment casting shell after the refractory mortar is hardened, referring to fig. 5.
In some embodiments of the invention, the wax outlet is capable of at least partially receiving the ceramic plug, and preferably completely receiving the ceramic plug.
Meanwhile, the size of the ceramic plug cannot be too smaller than that of the wax discharge port, so that the ceramic plug is easy to fall off.
Preferably, the diameter of the upper bottom surface of the circular truncated cone of the wax removal plug < the diameter of the first bottom surface of the ceramic plug, and the diameter of the second bottom surface of the ceramic plug < the diameter of the lower bottom surface of the circular truncated cone of the wax removal plug.
Optionally, in the process of placing the ceramic plug obtained in the step (b) into the wax discharge port of the calcined shell obtained in the step (a), pressing lightly to make the outer wall of the ceramic plug fit with the inner wall of the calcined shell provided with the wax discharge port.
In some specific embodiments of the present invention, after the shell is baked, the ceramic plug is mounted (placed) at a corresponding position of the dewaxing plug after dewaxing, that is, the ceramic plug is placed in a pore structure (cavity structure) formed by the dewaxing plug after dewaxing, and then the ceramic plug is fixed by using refractory mortar, so that the ceramic plug is prevented from being washed away during molten metal pouring, steel leakage is prevented, and the problem of casting inclusion caused by plugging a dewaxing opening is solved.
Wherein in step (c), the refractory mortar consists essentially of the second refractory material and the binder.
The wax removing plug and the ceramic plug matched with the wax removing plug are adopted, so that wax liquid can flow out in time and quickly, and foreign matters can be prevented from entering the inside of the shell. The problem of the shell spalling generated in the dewaxing (dewaxing) process of the shell in the prior art is solved, and the problem of casting inclusion caused by paint falling into the shell due to the fact that a wax outlet is blocked subsequently in the prior art is also solved.
Specifically, the wax removing plug and the ceramic plug provided by the invention can be produced in a plurality of sizes at one time, are suitable for various modules and runners with different sizes, and are convenient to produce as the wax removing plug is bonded on the runners when the modules are combined.
And the ceramic plug matched with the wax removing plug is adopted to plug the wax removing opening, and then the refractory mortar is matched, so that external impurities can be prevented from entering the shell, and the defect of inclusion of the casting is avoided.
In addition, because a casting pouring system is complex, in the shell dewaxing process in the prior art, wax melted at a position far away from a pouring cup is difficult to flow out of the shell quickly, and the shell is easy to burst. After the wax removing plugs are installed, wax (wax liquid) can quickly flow out of the pouring cup and the wax removing plugs, so that the dewaxing efficiency and quality are improved, the residue of the wax in the shell is reduced, and cracks of the shell in the dewaxing process can be reduced.
Preferably, in step (a), the wax discharging plug is mainly prepared by pressing low-temperature wax and/or medium-temperature wax. Wherein the melting point of the low-temperature wax is less than the melting point of the medium-temperature wax.
The wax discharging plug made of low-temperature wax and/or medium-temperature wax is convenient for discharging subsequent wax liquid.
Preferably, the low temperature wax has a melting point <60 ℃, including but not limited to any one of 59 ℃, 58 ℃, 56 ℃, 55 ℃, 53 ℃, 51 ℃, 50 ℃, 48 ℃, 45 ℃, 43 ℃, 40 ℃ or a range between any two; and/or the melting point of the medium-temperature wax is 70-80 ℃, including but not limited to any one of the values of 71 ℃, 72 ℃, 73 ℃, 74 ℃, 75 ℃, 76 ℃, 77 ℃, 78 ℃ and 79 ℃ or the range value between any two.
The wax removal plug can be directly pressed by low-temperature wax or pressed by medium-temperature wax. In some specific embodiments of the present invention, when the pressing is performed using the medium-temperature wax, a step of coating the surface of the medium-temperature wax with the low-temperature wax is further included after the pressing. Preferably, in the coating process, the temperature of the low-temperature wax is 90-100 ℃; including but not limited to any one of 91 deg.C, 92 deg.C, 93 deg.C, 94 deg.C, 95 deg.C, 96 deg.C, 97 deg.C, 98 deg.C, 99 deg.C or a range of values therebetween. More preferably, the coated low temperature wax has a thickness of 0.2mm or less, including but not limited to any one of 0.2mm, 0.18mm, 0.15mm, 0.13mm, 0.1mm, 0.08mm, 0.06mm, 0.05mm, 0.03mm, 0.01mm, or a range between any two.
If the low-temperature wax is directly adopted for pressing, the wax of the wax removal plug can be melted and flowed out before the part is dewaxed, so that the wax at the pouring gate part of the part can be conveniently discharged.
If the low-temperature wax is not provided with a ready-made wax pressing machine, the medium-temperature wax can be pressed and then is stained (coated) with a layer of low-temperature wax, and during dewaxing, the low-temperature wax is firstly melted and flows out, so that gaps appear, and the melting of the wax removal plug can be accelerated.
In some embodiments, the method further comprises the step of forming a wax plug compression mold before compressing the wax plug. Preferably, the wax plug die may be made of any conventional material, such as an aluminum alloy, preferably a wrought aluminum alloy. The number of the cavities of the wax removal plug compression mold is 4-6.
Preferably, in step (a), the wax discharging plug is in the shape of a combination of a first cylinder, a circular truncated cone and a second cylinder which are connected in sequence. I.e. in which the circular table is arranged between the first cylinder and the second cylinder, see fig. 2.
In some embodiments of the invention, the first cylinder is adapted to be coupled to a wax pattern die set. The cavity that the round platform formed is used for placing ceramic stopper, and the round platform structure can let the ceramic stopper of the same shape perfectly laminate, avoids the line contact to cause local stress too big and damage ceramic stopper, or the pouring process breakout problem. The second cylinder is used for prompting a cutting position, the length of the round table is not enough, and the ceramic plug cannot be thoroughly fixed.
Preferably, referring to fig. 2, the circular truncated cone comprises an upper bottom surface and a lower bottom surface, and the diameter of the upper bottom surface is less than that of the lower bottom surface; wherein the diameter of the upper bottom surface is more than or equal to that of the bottom surface of the first cylinder; and/or the diameter of the lower bottom surface < the diameter of the bottom surface of the second cylinder. That is, the diameter of the bottom surface of the first cylinder < the diameter of the bottom surface of the second cylinder.
Preferably, the diameter of the bottom surface of the first cylinder is 3-20 mm, including but not limited to the dot value of any one of 4mm, 5mm, 7mm, 9mm, 10mm, 12mm, 14mm, 15mm, 16mm, 18mm or the range value between any two.
And/or the height of the first cylinder is 5-50 mm, including but not limited to the dot value of any one of 7mm, 9mm, 10mm, 13mm, 15mm, 18mm, 20mm, 22mm, 25mm, 28mm, 30mm, 33mm, 35mm, 38mm, 40mm, 42mm, 45mm, 48mm or the range value between any two.
Preferably, the diameter of the bottom surface of the second cylinder is 6-40 mm, including but not limited to the point value of any one of 8mm, 10mm, 13mm, 15mm, 18mm, 20mm, 23mm, 25mm, 28mm, 30mm, 33mm, 35mm, 38mm or the range value between any two.
And/or the height of the second cylinder is 2-15 mm, including but not limited to the point value of any one of 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm or the range value between any two.
Preferably, an included angle α between the axis of the circular truncated cone and a straight line where a generatrix of the circular truncated cone is located is 5 ° to 30 °, including but not limited to a point value of any one of 6 °, 8 °, 10 °, 12 °, 15 °, 18 °, 20 °, 23 °, 25 °, 28 °, or a range value between any two of the values.
In some embodiments of the present invention, the method for connecting the wax discharging plug and the wax pattern module specifically comprises: and adhering one end of the wax removal plug, which is provided with the first cylinder, to the wax mould module. Preferably, the bonding is performed using a bonding wax. The adhesive wax may be any adhesive wax that is conventionally available commercially. For example, 135 adhesive wax, 509 adhesive wax, and the like. Preferably, the bonding positions comprise arbitrary and conventional wax discharge opening positions, and more preferably, the bonding positions are the positions where the wax pattern module is difficult to discharge wax (unsmooth wax discharge) and easy to crack. In the process of wax removal, the opening of the wax removal plug faces downwards, so that the wax removal plug conforms to the principle that water flows to the lower part, and the aim of smooth wax removal is fulfilled.
In some embodiments, the wax discharging plug is bent before being connected to the wax pattern module. Namely, the first cylinder of the wax discharging plug is bent to meet the requirement of the wax mould module on space. Any conventional bending mode can be adopted, and the bending mode can be selected according to actual needs.
In some specific embodiments of the present invention, an included angle γ formed between the axis of the wax discharging plug and the axis of the wax pattern module is 0 ° to 90 °, including but not limited to, a point value of any one of 85 °, 80 °, 75 °, 70 °, 65 °, 60 °, 55 °, 50 °, 45 °, 40 °, 35 °, 30 °, 25 °, 20 °, 15 °, 10 °, 5 °, 3 °, 2 °, 1 °, 0 °, or a range value between any two of them; preferably gamma.ltoreq.80 deg., more preferably gamma.ltoreq.60 deg.. The smaller the angle γ, the more favorable the outflow of the wax liquid during dewaxing.
Preferably, in the step (b), the ceramic plug is in the shape of a solid circular truncated cone, see fig. 3 and 4, or in the shape of a hollow circular truncated cone, see fig. 6.
In some specific embodiments of the present invention, when the ceramic plug is shaped as a hollow circular truncated cone, the cross-section of the ceramic plug is shaped as a V.
Preferably, the diameter of the first bottom surface of the ceramic plug is 3-20 mm, including but not limited to, any one of 5mm, 8mm, 10mm, 12mm, 15mm, 18mm, or a range therebetween. And/or the diameter of the second bottom surface of the ceramic plug is 10-30 mm, including but not limited to the point value of any one of 12mm, 15mm, 18mm, 20mm, 23mm, 25mm, 28mm or the range value between any two. Wherein the diameter of the first bottom surface is not equal to the diameter of the second bottom surface. Preferably, the diameter of the first bottom surface < the diameter of the second bottom surface.
Preferably, an included angle beta between the axis of the ceramic plug and a straight line where a generatrix of the axis is located is 5-30 degrees.
Preferably, when the diameter of the second bottom surface of the ceramic plug is >15mm (including but not limited to the point value of any one of 16mm, 18mm, 20mm, 22mm, 24mm, 25mm, 27mm, 29mm or the range value between any two), the shape of the ceramic plug is a hollow truncated cone, see fig. 6. More preferably, the ceramic plug has a thickness ≧ 4mm (including but not limited to any of 5mm, 7mm, 9mm, 10mm, 12mm, 14mm, 16mm, 18mm, or a range of values therebetween). Still further preferably, the thickness of the hollow ceramic plug in the direction along the axis thereof is the same as the thickness of the ceramic plug in the direction perpendicular to the generatrix thereof.
The ceramic plug is made into a hollow round table, so that the sintering yield can be increased, and the subsequent use is facilitated. Because the solid ceramic plug has larger shrinkage, cracking easily occurs, and the solid ceramic plug cannot be matched with a wax removal plug for use easily.
In some embodiments of the present invention, step (b) further comprises the step of forming a ceramic-plugged die prior to the step of pressing the ceramic plug, wherein the ceramic-plugged die can be made of any conventional material, such as steel, preferably 45# steel. More preferably, the number of the cavities of the ceramic-plugged compression mold is 4-6.
Preferably, an included angle α between the axis of the circular truncated cone of the wax removal plug and the straight line where the generatrix of the circular truncated cone is located is equal to an included angle β between the axis of the ceramic plug and the straight line where the generatrix of the ceramic plug is located. This enables the outer surface of the ceramic plug to conform to the inner surface of the fired shell.
Preferably, in step (b), the first refractory material comprises at least one of silica, alumina and zirconia, more preferably a mixture of the three materials.
The ceramic plug made of the first refractory material has high refractoriness and good stability.
Preferably, the ceramic plug is mainly prepared from the following components (through pressing) in parts by weight: 30-50 parts of silicon oxide (including but not limited to any of 33 parts, 35 parts, 38 parts, 40 parts, 42 parts, 45 parts, 48 parts or a range value therebetween), 40-60 parts of aluminum oxide (including but not limited to any of 42 parts, 44 parts, 45 parts, 47 parts, 49 parts, 50 parts, 52 parts, 55 parts, 57 parts, 59 parts or a range value therebetween), 5-15 parts of zirconium oxide (including but not limited to 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts or a range value therebetween), and 15-25 parts of wax (including but not limited to 16 parts, 17 parts, 19 parts, 20 parts, 22 parts, 24 parts or a range value therebetween).
The refractoriness of the ceramic plug prepared by the dosage is further improved, and the stability is better.
Preferably, the wax comprises beeswax. Wherein, beeswax is the wax that four pairs of wax glands excrete by honeybee (worker bee) belly, and beeswax (beeswax)'s chemical composition mainly includes: esters, free acids, free alcohols and hydrocarbons. Beeswax acts as a lubricant, provides fluidity to the material, and acts as a binder.
In some specific embodiments of the present invention, the silica has a particle size of 200 to 300 mesh, including but not limited to any one of 220 mesh, 250 mesh, 270 mesh or a range between any two. Preferably, the particle size of the alumina is 100 to 200 mesh, including but not limited to the point value of any one of 120 mesh, 150 mesh, 170 mesh or the range value between any two. Preferably, the zirconia has a particle size of 300 to 350 mesh, including but not limited to values of any one of 300 mesh, 325 mesh, 350 mesh or ranges between any two. The adoption of the raw materials with the granularity range is beneficial to further improving the refractoriness and stability of the prepared ceramic plug.
Preferably, in the step (b), the roasting temperature is 300-1200 ℃ (including but not limited to 350 ℃, 400 ℃, 450 ℃, 500 ℃, 550 ℃, 600 ℃, 650 ℃, 700 ℃, 750 ℃, 800 ℃, 850 ℃, 900 ℃, 950 ℃, 1000 ℃, 1050 ℃, 1100 ℃, 1150 ℃ or a range value between any two), and the roasting time is 4-11 h (including but not limited to 5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 10h, 10.5h or a range value between any two).
Preferably, in the step (b), the roasting specifically comprises: baking for 0.5-1.5 h (including but not limited to the dot value of any one of the 0, 290, 300, 320, 340 ℃ or the range value between any two) at 250-350 ℃ (including but not limited to the dot value of any one of the 270, 290, 300, 320, 340 ℃ or the range value between any two) for 0.5-1.5 h (including but not limited to the dot value of any one of the 0.5, 1, 1.5h or the range value between any two), then baking for 0.5-1.5 h (including but not limited to the dot value of any one of the 0.5, 1, 1.5h or the range value between any two) at 450-550 ℃ (including but not limited to the 470, 490, 500, 520, 540 ℃) for 650-750 ℃ (including but not limited to the 670, 690, 700, 720, 740 ℃ or the range value between any two) for 0.5-1.5 h (including but not limited to the 0.5h, 1, 1.5h or the range value between any two), then roasting for 3-6 h (including but not limited to any one of the values of 3.5h, 4h, 4.5h, 5h and 5.5h or the range value between any two) at 1120-1200 ℃ (including but not limited to 1130 ℃, 1150 ℃, 1170 ℃ and 1180 ℃) and taking out the roasted product after the temperature is reduced to below 200 ℃ (less than 200 ℃, including but not limited to any one of the values of 180 ℃, 150 ℃, 130 ℃, 100 ℃, 70 ℃, 50 ℃, 30 ℃ and 20 ℃) along with the furnace.
By adopting the roasting curve (multi-stage temperature rise), the problems of sintering cracking, insufficient sintering and unstable size caused by ceramic blockage can be avoided, so that the risk of casting inclusion scrapping caused by shell spalling and falling into scraps during subsequent shell preheating and pouring is avoided.
In some specific embodiments of the present invention, during the firing, the ceramic plug is first placed in a sagger filled with alumina powder, then a layer of alumina powder with a thickness of 100 to 150mm (including but not limited to a point value of any one of 105mm, 110mm, 120mm, 130mm, 140mm, 145mm or a range value between any two of them) is covered on the surface of the ceramic plug, and then the sagger is placed in a muffle furnace to perform the firing. Preferably, the particle size of the alumina powder is 100 to 200 meshes, including but not limited to any one of 110 meshes, 120 meshes, 130 meshes, 140 meshes, 150 meshes, 160 meshes and 180 meshes, or a range value between any two. The purpose of this firing is to allow the alumina powder to absorb the binder (beeswax) in the ceramic plug, and at the same time, to allow the ceramic plug to be heated uniformly.
Preferably, in step (c), the second refractory material comprises mullite; and/or, the binder comprises a silica sol.
In some specific embodiments of the present invention, the mullite has a particle size of 30 to 350 mesh, including but not limited to any one of 30 mesh, 40 mesh, 50 mesh, 60 mesh, 100 mesh, 150 mesh, 200 mesh, 270 mesh, 300 mesh, 325 mesh, or a range between any two thereof.
Preferably, the refractory mortar comprises the following components in parts by weight: 60-100 parts of mullite (including but not limited to values of any one of 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, 90 parts and 95 parts or ranges between any two) and 15-25 parts of silica sol (including but not limited to values of any one of 17 parts, 19 parts, 20 parts, 22 parts and 24 parts or ranges between any two).
In some specific embodiments of the present invention, the refractory mortar comprises the following components in parts by weight: 50-70 parts of mullite powder (including but not limited to any one of the point values of 53 parts, 55 parts, 58 parts, 60 parts, 63 parts, 65 parts and 68 parts or the range value between any two), 15-25 parts of mullite sand (including but not limited to any one of the point values of 17 parts, 19 parts, 20 parts, 22 parts and 24 parts or the range value between any two) and 15-25 parts of silica sol (including but not limited to any one of the point values of 17 parts, 19 parts, 20 parts, 22 parts and 24 parts or the range value between any two). Wherein the granularity of the mullite powder is smaller than that of the mullite sand. Preferably, the particle size of the mullite powder is 270-325 meshes (including but not limited to the point value of any one of 270 meshes, 300 meshes and 325 meshes or the range value between any two); the particle size of the mullite sand is 30-60 meshes (including but not limited to the point value of any one of 30 meshes, 40 meshes, 50 meshes and 60 meshes or the range value between any two).
By adopting the fire clay with specific composition, particularly adding the mullite powder and the mullite sand with different granularities, the sintering shrinkage of the fire clay can be reduced, and the fire clay is prevented from cracking in the heating process.
Wherein the refractory mortar is not easy to be over-diluted, and is placed on a horizontal ground after being kneaded into a ball by hands so as not to be scattered or collapsed.
Preferably, in step (c), the silica sol further comprises (is mixed with) an organic compound, more preferably a combustible organic compound. Wherein the silica sol is a dispersion liquid of nano silica particles in water. In some embodiments of the present invention, the organic compound is mixed with the silica sol to obtain the silica sol containing the organic compound.
The organic compound is mixed in the silica sol, so that the refractory mortar is beneficial to being ignited subsequently and hardened.
Preferably, the mass of the organic compound is 20% to 30% of the total mass of the silica sol, including but not limited to any one of 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or a range between any two.
Preferably, the organic compound includes at least one of methanol, ethanol, ethylene glycol, isopropanol, and acetone.
Preferably, in step (c), the hardening method comprises: and igniting the refractory mortar to harden the refractory mortar. And after the refractory mortar is hardened, the investment casting shell can be used, and can also be placed for 12-24 hours to be used after being dried.
The invention also provides a method for preparing an investment casting, which comprises the method for preparing the investment casting shell by using the wax removing plug and the ceramic plug.
The investment casting prepared by the method has high qualification rate and low rejection rate.
Compared with the prior art, the invention has the beneficial effects that:
(1) by arranging the wax removing plug, wax liquid can flow out in time and quickly, and the problem of unsmooth wax removing is solved.
(2) According to the invention, by arranging the ceramic plug matched with the wax removing plug, external impurities can be prevented from entering the shell, the defect of inclusion of the casting is avoided, and the rejection rate of the casting is reduced.
(3) The ceramic plug is fixed by the refractory mortar prepared from the specific components, so that the ceramic plug can be prevented from being washed away in the process of pouring molten metal, and steel leakage can be prevented.
(4) The ceramic plug with a specific composition provided by the invention has the advantages of high refractoriness and good stability.
(5) The wax removing plug and the ceramic plug provided by the invention can be produced in a plurality of sizes at one time, are suitable for various modules and runners with different sizes, and are bonded on the runners when the modules are combined, so that the production is convenient.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a front view of a wax removal plug provided by the present invention;
FIG. 2 is a front view of another wax removal plug provided by the present invention;
FIG. 3 is a front view of a ceramic plug provided by the present invention;
FIG. 4 is a front view of another ceramic plug provided by the present invention;
FIG. 5 is a schematic illustration of a ceramic plug placement location provided by the present invention;
FIG. 6 is a front view of yet another ceramic plug provided by the present invention;
fig. 7 is a schematic structural diagram of a wax pattern module according to embodiment 1 of the present invention;
fig. 8 is a schematic structural view of a wax pattern module according to embodiment 2 of the present invention;
fig. 9 is a schematic structural diagram of a wax pattern module according to embodiment 3 of the present invention.
Detailed Description
The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and the detailed description, but those skilled in the art will understand that the following described embodiments are some, not all, of the embodiments of the present invention, and are only used for illustrating the present invention, and should not be construed as limiting the scope of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The following examples and comparative examples are mainly used to illustrate the preparation method and the use method of the wax plug and the ceramic plug, and therefore, those in the examples and comparative examples, which do not indicate specific conditions, are performed according to conventional raw materials and the amounts thereof, conventional conditions or conventional parameters.
FIG. 1 is a front view of a wax removal plug provided by the present invention; FIG. 2 is a front view of another wax removal plug provided by the present invention; FIG. 3 is a front view of a ceramic plug provided by the present invention; FIG. 4 is a front view of another ceramic plug provided by the present invention; FIG. 5 is a schematic illustration of a ceramic plug placement location provided by the present invention; FIG. 6 is a front view of yet another ceramic plug provided by the present invention; FIG. 7 is a schematic structural view of a wax pattern module according to embodiment 1 of the present invention, further illustrating a bonding position of a portion of a wax discharging plug; FIG. 8 is a schematic structural view of a wax pattern module according to embodiment 2 of the present invention, further illustrating a bonding position of a portion of a wax discharging plug; fig. 9 is a schematic structural view of a wax pattern module provided in embodiment 3 of the present invention, in which the bonding position of the wax removing plug is also shown.
Example 1
The method for preparing an investment casting shell by using a wax removal plug and a ceramic plug provided by the embodiment comprises the following steps of:
(1) and preparing a dewaxing plug compression mould which is made of forged aluminum, wherein 4-6 cavities are formed.
Then pressing a wax removal plug: using medium-temperature wax, controlling the temperature of a wax cylinder and an injection tube to be 55-65 ℃, the injection pressure to be 1MPa, the injection time to be 30s, keeping the pressure for 20s, taking out the wax cylinder and the injection tube from a mold, and cooling the wax cylinder and the injection tube in water. After complete cooling, the wax is quickly immersed in a low-temperature wax jar at the temperature of 90-100 ℃ and immediately taken out, and the low-temperature wax is coated on the surface of the medium-temperature wax, so that the surface cannot flow. The thickness of the coated low-temperature wax is 0.1-0.2 mm.
The shape of each wax removal plug is an assembly of a first cylinder, a circular truncated cone and a second cylinder which are connected in sequence, and the combination is shown in figure 2. The diameter of the upper bottom surface of the circular truncated cone is 10mm, and an included angle alpha between the axis of the circular truncated cone and a straight line where a generatrix of the circular truncated cone is located is 16 degrees; the diameter of the bottom surface of the first cylinder is 10mm, and the height of the first cylinder is 5 mm; the diameter of the bottom surface of the second cylinder is 20mm, and the height of the second cylinder is 5 mm.
(2) After the wax pattern module is assembled, the wax removing plugs are adhered to one end of the annular wax pattern module with the diameter of 300 shown in fig. 7 by bonding wax, the wax removing plugs are symmetrically and uniformly distributed, the number of the wax removing plugs is 4 (only part of the wax removing plugs are shown in fig. 7, and part of the wax removing plugs are not shown), and an included angle gamma formed between the axis of each wax removing plug and the axis of the wax pattern module is 80 degrees.
(3) Coating a shell: preparing a surface layer by using a zircon powder silica sol coating (wherein the mass ratio of zircon powder to silica sol is 4-4.5: 1), and scattering corundum sand; manufacturing a reinforcing layer by using a mullite silica sol coating (wherein the mass ratio of mullite to silica sol is 2-2.5: 1), scattering mullite sand, and repeating the processes of slurry coating, sand scattering and drying for 6 times; and finally, sealing the layer by using mullite silica sol coating to obtain the shell.
(4) Dewaxing: before dewaxing, an angle grinder or a steel saw blade is used for cutting the dewaxing plug at the second cylinder far away from one end of the wax mould module, so that the wax inside the second cylinder is exposed, and the height of the second cylinder after cutting is 2 mm. Wherein the cutting is performed in a direction parallel to the bottom surface (upper bottom surface or lower bottom surface) of the second cylinder. Then, dewaxing was carried out in a high-temperature steam dewaxing kettle under a pressure of 0.9MPa for 10min, and the shell was checked for no cracking after dewaxing.
Wherein, the hole structure (cavity structure) formed by the dewaxing plug is the dewaxing port.
(5) Roasting the shell: and (3) roasting the shell in a sliding-bottom muffle furnace at the roasting temperature of 900 ℃ for 3h, and cooling to room temperature along with the furnace to obtain the roasted shell.
(6) Manufacturing a ceramic plug: firstly, preparing raw materials (core materials): 40 parts of silicon oxide with the granularity of 200-300 meshes, 50 parts of aluminum oxide with the granularity of 100-200 meshes, 10 parts of zirconium oxide with the granularity of 325 meshes and 18 parts of beeswax. Then, a core press and a compression mould are used for pressing the ceramic plug, wherein the compression mould is provided with 6 cavities, and the ceramic plug with three sizes can be obtained, which comprises the following specific steps:
1 #: the ceramic plug is in the shape of a hollow circular truncated cone (see fig. 6, the joint of the first bottom surface and the side surface of the ceramic plug has a certain radian), the diameter of the first bottom surface is 12mm, the diameter of the second bottom surface is 20mm, the included angle beta between the axis of the ceramic plug and the straight line where the generatrix is located is 16 degrees, the thickness of the ceramic plug in the direction along the axis is 5mm, and the thickness of the ceramic plug in the direction perpendicular to the generatrix is 5 mm.
2 #: the ceramic plug is in the shape of a hollow circular truncated cone (see fig. 6, the joint of the first bottom surface and the side surface of the ceramic plug has a certain radian), the diameter of the first bottom surface is 20mm, the diameter of the second bottom surface is 30mm, the included angle beta between the axis of the ceramic plug and the straight line where the generatrix is located is 10 degrees, and the thickness of the ceramic plug in the direction perpendicular to the generatrix is 5 mm.
3 #: the ceramic plug is in a solid round table shape (see fig. 4, the joint of the first bottom surface and the side surface of the ceramic plug has a certain radian), the diameter of the first bottom surface is 4mm, the diameter of the second bottom surface is 10mm, and an included angle beta between the axis of the ceramic plug and a straight line where the generatrix of the axis of the ceramic plug is located is 5 degrees.
Then, the ceramic blocks after pressing are placed in a sagger filled with alumina powder in a dispersed mode, a layer of alumina powder with the thickness of 100-150 mm is covered on the sagger, the sagger is placed in a muffle furnace, roasting is carried out according to a roasting curve of 300 ℃ multiplied by 1h +500 ℃ multiplied by 1h +700 ℃ multiplied by 1h + (1120-1200) DEG C multiplied by (3-6) h (namely roasting is carried out for 1h at 300 ℃, roasting for 1h at 500 ℃, then roasting for 1h at 700 ℃, roasting for 3-6 h at 1120-1200 ℃), and the sagger is cooled to be below 200 ℃ along with the furnace and taken out for later use. Wherein the granularity of the alumina powder is 100-200 meshes.
(7) Plugging a wax discharge port: and (4) cleaning the burrs on the outer part of the roasted shell obtained in the step (5), particularly removing the burrs on the periphery of the wax discharge port, then respectively placing the No. 1 ceramic plugs obtained in the step (6) into the wax discharge ports, and lightly pressing to ensure that the outer walls of the ceramic plugs are attached (tightly attached) to the inner walls of the roasted shell.
(8) And (3) fixing ceramic blockage: firstly, preparing refractory mortar, which comprises the following components: 60 parts of mullite powder with the granularity of 270 meshes, 20 parts of mullite sand with the granularity of 30-60 meshes and 20 parts of silica sol. Wherein the silica sol comprises ethanol, and the mass of the ethanol is 25% of the total mass of the silica sol. In the preparation process, the mullite powder and the mullite sand are uniformly mixed, then the silica sol containing ethanol is added into the mixture, and the mixture is uniformly stirred by a stirrer to obtain the refractory mortar. Wherein the refractory mortar is not easy to be over-diluted, and is placed on a horizontal ground after being kneaded into a ball by hands so as not to be scattered or collapsed.
Then, the prepared refractory mortar is adopted to fill the periphery of the ceramic plug, the refractory mortar is kneaded into a sheet shape by hand, the whole de-waxing plug and the ceramic plug are wrapped by the refractory mortar, and the refractory mortar is lightly pressed to be tightly attached to the shell. And then, igniting refractory mortar by using a lighter, and obtaining the investment casting shell after the refractory mortar is hardened.
Example 2
The method for preparing an investment casting shell using a wax-removing plug and a ceramic plug provided in this example includes the following steps:
(1) and preparing a dewaxing plug compression mould which is made of forged aluminum, wherein 4-6 cavities are formed.
Then pressing a wax removal plug: using low-temperature wax, controlling the temperature of a wax cylinder and an injection tube at 50-60 ℃, the injection pressure at 1.2MPa, the injection time at 20s, keeping the pressure at 20s, taking out the wax cylinder and the injection tube from a mold, and cooling the wax cylinder and the injection tube in water.
The shape of each wax removal plug is an assembly of a first cylinder, a circular truncated cone and a second cylinder which are connected in sequence, and the combination is shown in figure 2. The diameter of the upper bottom surface of the circular truncated cone is 20mm, and an included angle alpha between the axis of the circular truncated cone and a straight line where a generatrix of the circular truncated cone is located is 10 degrees; the diameter of the bottom surface of the first cylinder is 20mm, and the height of the first cylinder is 10 mm; the diameter of the bottom surface of the second cylinder is 35mm, and the height of the second cylinder is 15 mm.
(2) After the wax pattern module is assembled, the wax removing plugs are adhered to the bottom and the side of the 900-diameter annular wax pattern module shown in fig. 8 by using adhesive wax and are symmetrically and uniformly distributed, and the number of the wax removing plugs is 16 in total (all the wax removing plugs are not shown in fig. 8). The included angle gamma formed by the axis of the wax removing plug far away from one end of the pouring cup and the axis of the wax mould module (also the axis of the pouring cup) is 80 degrees, the included angle gamma formed by the axis of the wax removing plug positioned on the side surface and the axis of the wax mould module (also the axis of the pouring cup) is 60 degrees, and the included angle gamma formed by the axis of the wax removing plug close to one end of the pouring cup and the axis of the wax mould module (also the axis of the pouring cup) is 0 degrees.
(3) Coating a shell: substantially the same as the step (3) of example 1 except that the reinforcing layer pasting, sanding and drying processes were repeated 7 times.
(4) Dewaxing: before dewaxing, an angle grinder or a steel saw blade is used for cutting the dewaxing plug at the second cylinder far away from one end of the wax mould module, so that the wax inside the second cylinder is exposed, and the height of the second cylinder after cutting is 1 mm. Wherein the cutting is performed in a direction parallel to the bottom surface (upper bottom surface or lower bottom surface) of the second cylinder. Then, dewaxing was carried out in a high-temperature steam dewaxing kettle under a pressure of 0.6MPa for 20min, and the shell was checked for no cracking after dewaxing.
Wherein, the hole structure (cavity structure) formed by the dewaxing plug is the dewaxing port.
(5) Roasting the shell: and (3) roasting the shell in a sliding-bottom muffle furnace at 800 ℃ for 4h, and cooling to room temperature along with the furnace to obtain the roasted shell.
(6) Manufacturing a ceramic plug: firstly, preparing raw materials (core materials): 50 parts of silicon oxide with the granularity of 200-300 meshes, 40 parts of aluminum oxide with the granularity of 100-200 meshes, 5 parts of zirconium oxide with the granularity of 325 meshes and 15 parts of beeswax. Then, the ceramic plugs were pressed using a core press and a compression mold having 6 cavities, and the obtained ceramic plugs of three different sizes were the same as in example 1, and then fired, and the firing steps, conditions and parameters were the same as in example 1.
(7) Plugging a wax discharge port: and (3) cleaning the flash on the outside of the roasted shell obtained in the step (5), particularly removing the flash on the periphery of the wax discharge port, then respectively placing the 2# ceramic plug obtained in the step (6) into each wax discharge port, and lightly pressing to ensure that the outer wall of the ceramic plug is attached (tightly attached) to the inner wall of the roasted shell.
(8) And (3) fixing ceramic blockage: firstly, preparing refractory mortar, which comprises the following components: 70 parts of mullite powder with the granularity of 270 meshes, 15 parts of mullite sand with the granularity of 30-60 meshes and 15 parts of silica sol. Wherein the silica sol comprises methanol, and the mass of the methanol is 30% of the total mass of the silica sol. In the preparation process, the mullite powder and the mullite sand are uniformly mixed, then the silica sol containing the methanol is added into the mixture, and the mixture is uniformly stirred by a stirrer to obtain the refractory mortar. Wherein the refractory mortar is not easy to be over-diluted, and is placed on a horizontal ground after being kneaded into a ball by hands so as not to be scattered or collapsed.
Then, the prepared refractory mortar is adopted to fill the periphery of the ceramic plug, the refractory mortar is kneaded into a sheet shape by hand, the whole de-waxing plug and the ceramic plug are wrapped by the refractory mortar, and the refractory mortar is lightly pressed to be tightly attached to the shell. And then, igniting refractory mortar by using a lighter, and obtaining the investment casting shell after the refractory mortar is hardened.
Example 3
The method for preparing an investment casting shell using a wax-removing plug and a ceramic plug provided in this example includes the following steps:
(1) and preparing a dewaxing plug compression mould which is made of forged aluminum, wherein 4-6 cavities are formed.
Then pressing a wax removal plug: using low-temperature wax, controlling the temperature of a wax cylinder and an injection tube at 50-60 ℃, the injection pressure at 1.5MPa, the injection time at 20s, keeping the pressure at 20s, taking out the wax cylinder and the injection tube from a mold, and cooling the wax cylinder and the injection tube in water.
The shape of the wax removal plug is an assembly of a first cylinder, a round table and a second cylinder which are connected in sequence, and the combination is shown in figure 2. However, the size of the wax discharging plugs is different, wherein the size of the first kind of wax discharging plug is the same as that of the embodiment 2. And the size of the second wax removal plug is: the diameter of the upper bottom surface of the circular truncated cone is 3mm, and the included angle alpha between the axis of the circular truncated cone and the straight line where the generatrix of the circular truncated cone is located is 5 degrees; the diameter of the bottom surface of the first cylinder is 3mm, and the height of the first cylinder is 10 mm; the diameter of the bottom surface of the second cylinder is 8mm, and the height of the second cylinder is 3 mm.
(2) After the die set (wax die set) is assembled, the wax removing plugs are adhered to the bottom and the side of the turbine blade die set with the length of about 500mm by adopting adhesive wax and are symmetrically and uniformly distributed, and the number of the wax removing plugs is 6 in total. Wherein, 4 second wax removal plugs (the wax removal plugs with smaller sizes) are respectively arranged on the side surfaces of the two blade bodies, and 2 first wax removal plugs (the wax removal plugs with larger sizes) are arranged at the bottom. The included angle γ formed by the axis of the first wax removing plug (i.e. the wax removing plug with the larger size) at the bottom and the axis of the wax mold module (i.e. the axis of the pouring cup) is 60 °, and the included angle γ formed by the axis of the second wax removing plug (i.e. the wax removing plug with the smaller size) at the side and the axis of the wax mold module (i.e. the axis of the pouring cup) is 45 °.
(3) Coating a shell: same as in step (3) of example 2.
(4) Dewaxing: substantially the same as in step (4) of example 2 except that the height of the second cylinder after cutting was replaced with 1.5 mm.
(5) Roasting the shell: and (3) roasting the shell in a sliding-bottom muffle furnace at 1000 ℃ for 2h, and cooling to room temperature along with the furnace to obtain the roasted shell.
(6) Manufacturing a ceramic plug: firstly, preparing raw materials (core materials): 30 parts of silicon oxide with the granularity of 200-300 meshes, 60 parts of aluminum oxide with the granularity of 100-200 meshes, 15 parts of zirconium oxide with the granularity of 300 meshes and 25 parts of beeswax. Then, the ceramic plugs were pressed using a core press and a compression mold having 6 cavities, and the obtained ceramic plugs of three different sizes were the same as in example 1, and then fired, and the firing steps, conditions and parameters were the same as in example 1.
(7) Plugging a wax discharge port: and (3) cleaning the flash on the outside of the roasted shell obtained in the step (5), particularly removing the flash on the periphery of the wax discharge port, then respectively placing the ceramic plug No. 2 and the ceramic plug No. 3 obtained in the step (6) into the wax discharge ports, and lightly pressing to ensure that the outer wall of the ceramic plug is attached (tightly attached) to the inner wall of the roasted shell.
(8) And (3) fixing ceramic blockage: firstly, preparing refractory mortar, which comprises the following components: 50 parts of mullite powder with the granularity of 270 meshes, 25 parts of mullite sand with the granularity of 30-60 meshes and 25 parts of silica sol. Wherein the silica sol comprises acetone, and the mass of the acetone is 20% of the total mass of the silica sol. In the preparation process, the mullite powder and the mullite sand are uniformly mixed, then the silica sol containing acetone is added into the mixture, and the mixture is uniformly stirred by a stirrer to obtain the refractory mortar. Wherein the refractory mortar is not easy to be over-diluted, and is placed on a horizontal ground after being kneaded into a ball by hands so as not to be scattered or collapsed.
Then, the prepared refractory mortar is adopted to fill the periphery of the ceramic plug, the refractory mortar is kneaded into a sheet shape by hand, the whole de-waxing plug and the ceramic plug are wrapped by the refractory mortar, and the refractory mortar is lightly pressed to be tightly attached to the shell. And then, igniting refractory mortar by using a lighter, and obtaining the investment casting shell after the refractory mortar is hardened.
Comparative example 1
The method of preparing an investment casting shell using a wax-removing rod according to the present comparative example comprises the steps of:
(1) pressing a wax discharging rod: using medium-temperature wax, controlling the temperature of a wax cylinder and an injection tube to be 55-65 ℃, the injection pressure to be 1MPa, the injection time to be 30s, keeping the pressure for 20s, taking out the wax cylinder and the injection tube from a mold, and cooling the wax cylinder and the injection tube in water. Wherein the size of the wax removing rod is as follows
(2) After the wax pattern module is assembled, the wax removing rods are bonded to the bottom of the 300-diameter annular wax pattern module shown in fig. 7 by bonding wax and are symmetrically and uniformly distributed, the number of the wax removing rods is 4, and an included angle formed by the axis of the wax removing rods and the axis of the wax pattern module (which is also the axis of the sprue cup) is 90 degrees.
(3) Coating a shell: same as in step (3) in example 1.
(4) Dewaxing: before dewaxing, a pair of pliers is used for breaking off half of the wax removing rod to expose wax inside, and then dewaxing is carried out in a high-temperature steam dewaxing kettle under the pressure of 0.6-0.9 MPa for 10-20 min. The shell was inspected for local cracking after dewaxing.
(5) Roasting the shell: same as in step (5) in example 1.
(6) Preparing a coating by using mullite powder with the granularity of 270 meshes and silica sol according to the mass ratio of 5:1, directly plugging a wax discharge opening with the coating, and drying the coating to obtain the investment casting shell.
While particular embodiments of the present invention have been illustrated and described, it will be appreciated that the above embodiments are merely illustrative of the technical solution of the present invention and are not restrictive; those of ordinary skill in the art will understand that: modifications may be made to the above-described embodiments, or equivalents may be substituted for some or all of the features thereof without departing from the spirit and scope of the present invention; the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention; it is therefore intended to cover in the appended claims all such alternatives and modifications that are within the scope of the invention.
Claims (10)
1. The method for preparing the investment casting shell by using the wax removing plug and the ceramic plug is characterized by comprising the following steps of:
(a) after the wax removal plug is connected with the wax mould module, coating and hanging paint on the surface of the wax removal plug and sanding to obtain a shell; sequentially dewaxing and roasting the shell to obtain a roasted shell;
the wax removal plug is mainly prepared by pressing wax, and the shape of the wax removal plug comprises a cylinder and/or a circular truncated cone;
(b) pressing the ceramic plug, and roasting the ceramic plug;
the ceramic plug is mainly prepared by pressing a first refractory material and wax, and the ceramic plug is in a shape of a circular truncated cone;
(c) putting the ceramic plug obtained in the step (b) into the wax discharge port of the roasted shell obtained in the step (a), then coating refractory mortar on the surfaces of the ceramic plug and the wax discharge port, and obtaining the investment casting shell after the refractory mortar is hardened;
wherein the refractory mortar is mainly composed of a second refractory material and a binder.
2. The method of preparing an investment casting shell using a wax-drain plug and a ceramic plug according to claim 1, wherein in step (a), the wax-drain plug is mainly prepared by pressing low temperature wax and/or medium temperature wax;
preferably, the low temperature wax has a melting point <60 ℃; and/or the melting point of the medium-temperature wax is 70-80 ℃.
3. The method of making an investment casting shell using a wax-drain plug and a ceramic plug of claim 1 wherein in step (a), the wax-drain plug is shaped as a combination of a first cylinder, a truncated cone, and a second cylinder connected in series;
preferably, the circular truncated cone comprises an upper bottom surface and a lower bottom surface, and the diameter of the upper bottom surface is less than that of the lower bottom surface; wherein the diameter of the upper bottom surface is more than or equal to that of the bottom surface of the first cylinder; and/or the diameter of the lower base < the diameter of the base of the second cylinder;
preferably, the diameter of the bottom surface of the first cylinder is 3-20 mm; and/or the height of the first cylinder is 5-50 mm;
preferably, the diameter of the bottom surface of the second cylinder is 6-40 mm; and/or the height of the second cylinder is 2-15 mm;
preferably, an included angle alpha between the axis of the circular truncated cone and a straight line where a generatrix of the circular truncated cone is located is 5-30 degrees.
4. The method of making an investment casting shell utilizing a wax-drain plug and a ceramic plug of claim 3 wherein in step (b) said ceramic plug is in the shape of a solid frustum or a hollow frustum;
preferably, the diameter of the first bottom surface of the ceramic plug is 3-20 mm, and/or the diameter of the second bottom surface of the ceramic plug is 10-30 mm;
preferably, an included angle beta between the axis of the ceramic plug and a straight line where the generatrix of the axis is located is 5-30 degrees;
preferably, when the diameter of the second bottom surface of the ceramic plug is greater than 15mm, the ceramic plug is in the shape of a hollow circular truncated cone; wherein the thickness of the ceramic plug is more than or equal to 4 mm.
5. The method of making an investment casting shell utilizing a wax-drain plug and a ceramic plug of claim 4 wherein said included angle α is equal to said included angle β.
6. The method of making an investment casting shell utilizing a wax-drain plug and a ceramic plug of claim 1 wherein in step (b) the first refractory material comprises at least one of silica, alumina and zirconia;
preferably, the ceramic plug is mainly prepared from the following components in parts by weight: 30-50 parts of silicon oxide, 40-60 parts of aluminum oxide, 5-15 parts of zirconium oxide and 15-25 parts of wax;
preferably, the wax comprises beeswax.
7. The method for preparing an investment casting shell using a wax discharging plug and a ceramic plug according to claim 1, wherein in the step (b), the roasting temperature is 300 to 1200 ℃, and the roasting time is 4 to 11 hours;
preferably, in the step (b), the roasting specifically comprises: roasting at 250-350 ℃ for 0.5-1.5 h, then roasting at 450-550 ℃ for 0.5-1.5 h, then roasting at 650-750 ℃ for 0.5-1.5 h, and then roasting at 1120-1200 ℃ for 3-6 h.
8. The method of making an investment casting shell utilizing a wax-drain plug and a ceramic plug of claim 1 wherein in step (c) the second refractory material comprises mullite; and/or, the binder comprises silica sol;
preferably, the refractory mortar comprises the following components in parts by weight: 60-100 parts of mullite and 15-25 parts of silica sol.
9. The method for preparing an investment casting shell using a wax-drain plug and a ceramic plug according to claim 1, wherein in step (c), the silica sol comprises an organic compound;
preferably, the mass of the organic compound is 20-30% of the total mass of the silica sol;
preferably, the organic compound includes at least one of methanol, ethanol, ethylene glycol, isopropanol, and acetone;
preferably, in step (c), the hardening method comprises: and igniting the refractory mortar to harden the refractory mortar.
10. A method of making an investment casting comprising the method of making an investment casting shell according to any one of claims 1 to 9 using a wax-drain plug and a ceramic plug.
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| CN202210750790.XA CN115069980A (en) | 2022-06-28 | 2022-06-28 | Method for preparing investment casting shell by using wax removal plug and ceramic plug and application thereof |
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| CN202210750790.XA CN115069980A (en) | 2022-06-28 | 2022-06-28 | Method for preparing investment casting shell by using wax removal plug and ceramic plug and application thereof |
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Cited By (1)
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| CN115889688A (en) * | 2022-12-09 | 2023-04-04 | 中国航发北京航空材料研究院 | Method for preventing foreign matters from entering inner cavity of hollow turbine blade |
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Inventor after: Du Hongqiang Inventor after: Xu Songming Inventor after: Liu Haoran Inventor after: Meng Xiaodong Inventor after: Chen Xingfu Inventor after: Fu Yanliang Inventor before: Du Hongqiang Inventor before: Xu Songming Inventor before: Liu Haoran Inventor before: Chen Xingfu Inventor before: Fu Yanliang |