Method for calculating mold opening compensation angle of multi-union guide vane

Abstract

The invention discloses a method for calculating a mold opening compensation angle of a multi-linkage guide vane, which comprises the following steps of: firstly, referring to an existing single-linkage vane mold opening shrinkage rate of a similar casting, scaling a digital model of the casting according to the shrinkage rate, printing a wax mold through 3D printing equipment, assembling the printed wax mold according to a precision investment casting method, making a shell, dewaxing, roasting, pouring, removing the shell, and blowing sand, so as to obtain the mold opening compensation angle of the multi-linkage guide vane. And then blue light three-dimensional scanning is carried out on the casting, local optimum fitting is carried out on the multi-union blade, the deflection displacement amount of a positioning point is calculated, an included angle formed by the deflection displacement amount and a coordinate system is obtained, and therefore the compensation angle needed by final mold opening is calculated. The method is simple and practical, does not need to design a special mold, is short in production period and low in test cost, and is particularly suitable for mold opening design of the multi-connected turbine guide vane with a complex appearance structure.

Description

Technical Field

[0001] The invention belongs to the technical field of investment precision casting, and in particular relates to a method for calculating the compensation angle of a multi-guide vane mold opening. Background Art

[0002] The trend of turbine guide vanes being designed from single-unit structures to multi-unit structures is gradually increasing. However, it is difficult to open the mold for multi-unit guide vanes as a whole, and there are the following problems: 1. The structure of multi-guide vanes is complex. Conventional single-guide vane shrinkage usually only needs to be calculated in the three-dimensional directions of X, Y, and Z. Figure 1 As shown, due to the increase in the number of guide vanes, a shrinkage compensation angle along the circumference of the guide vane engine axis is also required (the compensation angle for single guide vanes can be ignored), as shown Figure 2 If the design is not good, it will easily lead to the casting position and throat size out of tolerance.

[0003] 2. Some multi-guide vane mold design ideas adopt a method of assembling single-guide vanes into multiple guide vanes through tooling, or splitting and assembling the blade body and edge plate. However, this method is cumbersome to operate, requires high worker proficiency, and cannot guarantee consistency, making it unsuitable for mass production.

[0004] 3. The multi-guide vane mold adopts an integral mold. If the shrinkage rate design is not accurate, subsequent mold repair will be difficult, the mold repair cost will be high, and the repair cycle will be long. Summary of the Invention

[0005] The main purpose of this method is to provide a method for calculating the compensation angle of the multi-guide vane mold opening. This method combines blue light scanning detection and 3D printing wax mold technology to calculate the compensation angle value required for mold opening more accurately, ensuring the realization of the overall mold opening of the multi-blade integral mold.

[0006] To this end, the present invention provides a method for calculating the compensation angle of the multi-guide vane mold opening, comprising the following steps: Step 1: First, according to the single guide vane mold opening idea, preset an initial shrinkage rate in the X, Y, and Z directions for the multi-guide vanes, and scale the casting model in the 3D software; Step 2: Use 3D printing equipment to print out a wax model of the scaled digital model; Step 3: The printed wax model is assembled, shelled, dewaxed, fired, poured, and shelled according to the method of investment casting to obtain a multi-guide vane casting; Step 4: Perform a blue light 3D scan of the casting. The multi-guide vane casting has six positioning points, including a positioning point B on the back of the guide vane. Use the blue light device to issue a report based on the six-point positioning method, analyze the size pattern of the guide vane farthest from the positioning point, and then use the local best fitting method of the blue light device to fit the guide vane to a uniform state on the back of the basin. After fitting, the guide vane is rotated a certain angle along the circumferential direction, and the positioning point B is moved from the original B position to the B' position. The blue light 3D software calculates the displacement △s of the positioning point B on the back of the blade after moving along the circumferential rotation direction of the guide vane to B'. The displacement of the positioning point before and after the movement forms an angle θ with the original coordinate system of the guide vane. Step 4: Calculate the required mold opening compensation angle △θ for each guide vane through the included angle θ. , n is the number of multiple guide vanes; Step 5: The final mold opening shrinkage rate is set as the shrinkage rate in the X, Y, and Z directions. Then, the multi-guide vanes are split into each guide vane in the 3D software. Except for the guide vane where the positioning point B is located, each guide vane is rotated separately to increase the compensation angle △θ required for mold opening.

[0007] Specifically, the scaled digital model is printed out into a wax model using a 3D printing device, and the printed wax model is melted to remove the supporting wax material that prevents the wax model from deforming, thereby obtaining a complete wax model with the initial shrinkage rate released.

[0008] Specifically, the pouring system and mold assembly plan are designed in advance, and the printed wax mold is welded according to the mold assembly plan. Attention should be paid to the protection of the wax mold during the welding process. At the same time, it should be carried out in a special constant temperature and humidity workshop to prevent deformation of the wax mold.

[0009] Specifically, after the mold is assembled, Al2O3 powder and sand are used to prepare the mold shell layer by layer by adopting the slurry sand sprinkling method. After the mold shell is prepared, a dewaxing kettle is used to remove the wax inside the mold shell. At the same time, in order to ensure the high-temperature strength of the mold shell and remove the residual wax, the mold shell is baked.

[0010] Specifically, after the mold shell is baked, it is cooled to room temperature and cleaned with clean tap water to rinse out the particulate inclusions inside the mold shell as much as possible. Then, a penetration inspection is performed with methylene blue + alcohol reagent to ensure that there are no obvious cracks visible to the naked eye in the mold shell. The mold shell is then dried at about 200-300℃ to remove excess moisture.

[0011] Specifically, prepare the alloy of the same grade as required for the casting, load the mold shell and the alloy into the vacuum precision casting furnace, heat the mold shell to the specified temperature according to the process specification document, melt the alloy and measure the temperature, and after reaching the specified pouring temperature, cast the formed multi-guide vane casting.

[0012] Specifically, the casting is shelled, redundant runners and risers are removed, and the surface of the multi-guide vane casting is sandblasted.

[0013] The present invention makes use of the most advanced blue-light 3D scanning and 3D printing technologies. First, referring to the mold shrinkage rate of a single-blade of a similar casting, the digital model of the casting is scaled according to the shrinkage rate, and then a wax mold is printed by a 3D printing device. The printed wax mold is assembled, shelled, dewaxed, roasted, poured, shelled, and sand-blown according to the method of investment casting. Then, a blue-light 3D scan is performed on the casting, and a local optimal fit is performed on the multi-blade. The deflection displacement △s of the positioning point is calculated, and the angle θ with the coordinate system is obtained, thereby calculating the compensation angle required for the final mold opening.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. Simple and practical, no need to design special molds, short production cycle, low test cost, especially suitable for the mold opening design of multi-turbine guide vanes with complex appearance and structure.

[0015] 2. By 3D printing wax patterns, it is possible to verify whether the initial shrinkage rates in the three-dimensional directions of X, Y, and Z are reasonable, avoiding situations where they are too large or too small. At the same time, a round of test verification of the metallurgical results of the casting can be carried out, saving test cycles.

[0016] 3. Combining blue light 3D scanning detection and 3D printing technology, we can obtain reliable data on the mold opening compensation angle required for multi-blades, ensuring the overall mold opening of the multi-blade mold, saving mold repair costs, and greatly increasing the convenience of subsequent on-site operations, ensuring the consistency of multi-blade products, and thus improving the qualified rate of product dimensions. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 It is a schematic diagram of the three-dimensional direction of the guide vane contraction rate; Figure 2 It is a schematic diagram of the contraction direction of the multiple guide vanes; Figure 3 This is a schematic diagram of the movement of the multi-guide vane positioning points after fitting; Figure 4 This is a schematic diagram of multiple guide vanes after increasing the compensation angle; Figure 5 It is a schematic diagram of the multi-guide vane module scheme. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0020] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0022] A method for calculating a multi-guide vane mold opening compensation angle includes the following steps: Step 1: First, according to the idea of ​​single guide vane mold opening, preset an initial shrinkage rate in the X, Y, and Z directions for the multi-guide vane, and scale the casting model in the 3D software.

[0023] Step 2: Use 3D printing equipment to print out a wax model from the scaled digital model. Remove the supporting wax material that prevents the wax model from deforming from the printed wax model to obtain a complete wax model with the initial shrinkage rate released.

[0024] Step 3: Design the pouring system and mold assembly plan in advance, including the pouring cup, runner, riser, etc., and weld the printed wax mold according to the mold assembly plan. Pay attention to the protection of the wax mold during the welding process. At the same time, it should be carried out in a special constant temperature and humidity workshop to prevent deformation of the wax mold.

[0025] Step 4: After the mold is assembled, use Al2O3 powder and sand to prepare the shell layer by layer using the slurry and sand sprinkling method. After the shell is prepared, use a dewaxing kettle to remove the wax inside the shell. At the same time, in order to ensure the high-temperature strength of the shell and remove the residual wax, the shell is baked.

[0026] Step 5: After the mold shell is baked, it is cooled to room temperature and cleaned with clean tap water to rinse out any possible particulate inclusions inside the mold shell as much as possible. Then, a penetration inspection is performed with methylene blue + alcohol reagent to ensure that there are no obvious cracks visible to the naked eye on the mold shell. The mold shell is then dried at about 200-300℃ to remove excess moisture.

[0027] Step 6: Prepare the alloy of the same grade as that required for the casting, load the mold shell and the alloy into the vacuum precision casting furnace (if the casting is an equiaxed crystal casting, the mold shell needs to be preheated separately), heat the mold shell to the specified temperature according to the process specification document, melt the alloy and measure the temperature. After reaching the specified pouring temperature, pour the molded casting.

[0028] Step 7: Shell the casting, remove excess runners and risers, clean any metal burrs that may exist on the casting surface, and sandblast the casting surface.

[0029] Step 8: The casting is scanned in 3D with blue light. The multi-guide vane structure has six positioning points, among which the guide vane back position is usually set with positioning point B. The blue light device is used to issue an RPS report based on the six-point positioning method to analyze the size pattern of the guide vane farthest from the positioning point. Then, the local best fitting method of the blue light device is used to fit the guide vane to the uniform state of the basin back. After fitting, the guide vane is rotated a certain angle along the circumferential direction, and the positioning point B is moved from the original B position to Figure 3 The B' position is calculated by the Blue Light 3D software. The displacement △s of the positioning point B on the back of the blade moves along the circumferential rotation direction of the guide vane to B'. Before and after the displacement of the positioning point moves, an angle θ is formed with the original coordinate system of the guide vane.

[0030] Step 9: Through the included angle θ, the required mold opening compensation angle △θ for each guide vane can be calculated. Assuming that the number of multi-guide vanes is n, the compensation angle .

[0031] Step 10: Therefore, the final mold opening shrinkage rate can be determined as the shrinkage rate in the X, Y, and Z directions. Then, the multi-guide vanes are split into each guide vane in the 3D software. Except for the guide vane where the positioning point B is located, each guide vane is rotated separately to increase the compensation angle required for mold opening. ,like Figure 4 .

[0032] The present invention uses 3D printed wax patterns to verify the rationality of the initial shrinkage rates in the three-dimensional X, Y, and Z directions, avoiding over- or under-settings. This allows for a single round of experimental verification of the casting metallurgical results, saving test cycles. Combining blue-light 3D scanning and 3D printing technology, reliable data on the required mold opening compensation angles for multi-joint blades is obtained, ensuring the complete opening of the mold for the multi-joint blades, saving mold repair costs, and significantly increasing the convenience of subsequent on-site operations, ensuring the consistency of the multi-joint blade products and improving the product dimensional qualification rate.

[0033] Application Examples In this application example, the multi-guide vane is a 4-unit structure with a maximum outline size of 127×58×42mm. The casting material is nickel-based high-temperature alloy K447A. The casting is produced by investment casting. The blade profile tolerance is required to be ±0.1mm, and the position tolerance is required to be ±0.2mm. The dimensions are relatively strict.

[0034] like Figure 1 As shown, the casting is given an initial shrinkage rate of 1.6-1.8% in the X, Y, and Z directions. The casting model is scaled in 3D software such as UG or SolidWorks, and the digital model is exported to the 3D printing device. The wax mold is 3D printed according to the given digital model. Pay attention to setting the support wax during printing to prevent deformation of the wax part. In this example, the purple wax material is the wax part model wax, and the white wax material is the wax part support wax. The software automatically generates the support wax for the casting in 3D space.

[0035] After the wax part is printed, it is placed in a specially prepared container of alcohol-based organic solvent. Heating and magnetic stirring are used to dissolve the white support wax. To prevent deformation at high temperatures, the heating temperature must not exceed 40°C. The wax part must also be placed on a porous platform support to facilitate the dissolution of the white support wax while preventing it from colliding with the container. The complete dissolution of the white support wax takes 20 to 40 minutes. During this process, the wax dissolution status should be monitored in real time to remove the desired purple wax part.

[0036] according to Figure 5 The mold assembly method shown is used, using top-injection molding. The mold assembly structure involved includes the pouring cup 1, wax outlet 2, runner 3, support rod 4, riser 5, and wax component 6. Except for the wax component, which is 3D printed, and the pouring cup, which is prepared using a universal mold, the remaining mold assembly structures can be manually processed with wax. The above structures are spliced ​​and welded with an electric soldering iron. Ensure that all joints are firmly welded, without any cold or leaking welds, to prevent the module from falling apart during subsequent shell production due to unstable welding.

[0037] The mold shell is prepared by the method of investment casting. The mold shell used in this example is a silica sol-alumina composite mold shell system, which is dipped in slurry and sanded layer by layer. The shell thickness is 5.5 layers and the mold shell thickness is 5-7mm. The prepared mold shell undergoes dewaxing, roasting, cleaning and drying processes, and is then ready for pouring.

[0038] The shell is wrapped with aluminum silicate insulation cotton to prevent local metallurgical defects such as looseness. The wrapped shell is preheated at a temperature of 1000-1100°C and the preheating and insulation time is ≥4h.

[0039] In a vacuum investment casting furnace, vacuum is applied to melt K447A alloy in a pre-knotted and dried crucible (waste materials such as pouring risers can be used to save costs). The alloy weighs 10 to 15 kg, and the pouring temperature is controlled at 1450 to 1500°C. The preheated mold shell is placed in the vacuum investment casting furnace and vacuum is applied for pouring.

[0040] After the casting is shelled, the remaining risers are cut off, and the excess burrs are cleaned, the sand is blown and the blue light three-dimensional scanning is performed. The back of the multi-guide vane is provided with a positioning point B. The blue light equipment is used to issue an RPS report according to the six-point positioning method to analyze the size law of the guide vane farthest from the positioning point. Figure 3 The 4# blade in the middle is fitted locally to the best fit, and the guide vane is fitted to the uniform state of the basin back. After the fitting is completed, the guide vane actually rotates a certain angle along the circumferential direction, and the positioning point is moved from the original B position to Figure 3 The Blu-ray 3D software calculates the displacement △s of the positioning point B on the back of the blade after it moves along the circumferential rotation direction of the guide vane to B', △s = 0.24mm. Before and after the displacement of the positioning point, an angle θ is formed with the original coordinate system of the guide vane, θ = 0.1301°.

[0041] By using the included angle θ=0.1301°, the required mold opening compensation angle △θ for each guide vane can be calculated. If the number of the multi-guide vanes is 4, the compensation angle .

[0042] The final mold opening plan for the blade was to first design an initial shrinkage rate of 1.6-1.8%, and then add a compensation angle to each blade. Subsequent physical mold opening and casting verification showed that the mold opening dimensions met the requirements and no mold modification was required.

[0043] The present invention makes use of the most advanced blue light 3D scanning and 3D printing technology. First, referring to the existing single-blade mold opening shrinkage rate of similar castings, the digital model of the casting is scaled according to the shrinkage rate, and then a wax mold is printed by a 3D printing device. The printed wax mold is assembled, shelled, dewaxed, roasted, poured, shelled, and sandblasted according to the method of investment casting. After that, the casting is scanned in blue light 3D, and the multi-blade is locally optimally fitted. The deflection displacement △s of the positioning point is calculated, and the angle θ formed with the coordinate system is obtained, thereby calculating the compensation angle required for the final mold opening. .

[0044] Unless otherwise stated, for any of the technical solutions disclosed in the present invention, if a numerical range is disclosed, the disclosed numerical range is a preferred numerical range. Any person skilled in the art should understand that the preferred numerical range is merely a numerical range that is representative or has a more obvious technical effect among many feasible numerical values. Due to the large number of numerical values, it is impossible to enumerate them exhaustively. Therefore, the present invention discloses some numerical values ​​to illustrate the technical solutions of the present invention. Moreover, the numerical values ​​listed above should not be construed as limiting the scope of protection of the present invention.

[0045] At the same time, if the above-mentioned invention discloses or involves components or structural parts that are fixedly connected to each other, then, unless otherwise stated, the fixed connection can be understood as: a detachable fixed connection (for example, using bolts or screws to connect), and can also be understood as: a non-detachable fixed connection (for example, riveting, welding). Of course, the mutual fixed connection can also be replaced by an integrated structure (for example, manufactured by a casting process) (except where it is obviously impossible to use an integrated forming process).

[0046] In addition, unless otherwise stated, terms used in any of the technical solutions disclosed herein to represent positional relationships or shapes include states or shapes that are similar, analogous, or approximate. Any component provided by the present invention may be assembled from multiple separate components or may be a single component manufactured using an integral molding process.

[0047] The above embodiments are merely examples to clearly illustrate the present invention and are not intended to limit its implementation. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to provide an exhaustive list of all embodiments. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for calculating the compensation angle of the multi-guide vane mold opening, characterized in that: The steps include: Step 1: First, according to the single guide vane mold opening idea, preset an initial shrinkage rate in the X, Y, and Z directions for the multi-guide vanes, and scale the casting model in the 3D software; Step 2: Use 3D printing equipment to print out a wax model of the scaled digital model; Step 3: The printed wax model is assembled, shelled, dewaxed, fired, poured, and shelled according to the method of investment casting to obtain a multi-guide vane casting; Step 4: Perform a blue light 3D scan of the casting. The multi-guide vane casting has six positioning points, including a positioning point B on the back of the guide vane. Use the blue light device to issue a report based on the six-point positioning method, analyze the size pattern of the guide vane farthest from the positioning point, and then use the local best fitting method of the blue light device to fit the guide vane to a uniform state on the back of the basin. After fitting, the guide vane is rotated a certain angle along the circumferential direction, and the positioning point B is moved from the original B position to the B' position. The blue light 3D software calculates the displacement △s of the positioning point B on the back of the blade after moving along the circumferential rotation direction of the guide vane to B'. The displacement of the positioning point before and after the movement forms an angle θ with the original coordinate system of the guide vane. Step 4: Calculate the required mold opening compensation angle Δθ for each guide vane through the included angle θ. , n is the number of multiple guide vanes; Step 5: The final mold opening shrinkage rate is set as the shrinkage rate in the X, Y, and Z directions. Then, the multi-guide vanes are split into each guide vane in the 3D software. Except for the guide vane where the positioning point B is located, each guide vane is rotated separately to increase the compensation angle Δθ required for mold opening.

2. The method according to claim 1, wherein: The scaled digital model is printed out into a wax model using a 3D printing device. The printed wax model is then melted to remove the supporting wax material that prevents the wax model from deforming, obtaining a complete wax model after releasing the initial shrinkage rate.

3. The method according to claim 1, wherein: Design the pouring system and mold assembly plan in advance, and weld the printed wax mold according to the mold assembly plan. Pay attention to the protection of the wax mold during the welding process. At the same time, it is carried out in a special constant temperature and humidity workshop to prevent deformation of the wax mold.

4. The method according to claim 1, wherein: After the mold is assembled, Al2O3 powder and sand are used to prepare the mold shell layer by layer by adopting the slurry sand sprinkling method. After the mold shell is prepared, a dewaxing kettle is used to remove the wax inside the mold shell. At the same time, in order to ensure the high-temperature strength of the mold shell and remove the residual wax, the mold shell is baked.

5. The method according to claim 1, wherein: After the mold shell is baked, it is cooled to room temperature and cleaned with clean tap water to rinse out the particulate inclusions inside the mold shell as much as possible. Then, a penetration inspection is performed with methylene blue + alcohol reagent to ensure that there are no obvious cracks visible to the naked eye on the mold shell. The mold shell is then dried at about 200-300℃ to remove excess moisture.

6. The method according to claim 1, wherein: Prepare the alloy of the same grade as that required for the casting, load the mold shell and the alloy into the vacuum precision casting furnace, heat the mold shell to the specified temperature according to the process specification document, melt the alloy and measure the temperature. After reaching the specified pouring temperature, cast the formed multi-guide vane casting.

7. The method according to claim 1, wherein: The casting is shelled, the redundant runners and risers are removed, and the surface of the multi-guide vane casting is sandblasted.

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