Large high-temperature alloy blank casting method capable of controlling casting size

Abstract

The invention relates to a large-scale high-temperature alloy blank casting method capable of controlling the casting size, and belongs to the technical field of high-temperature alloy casting. Measuring a temperature curve of the sand mold after the high-temperature alloy is poured; a process model is created, simulation software is used for carrying out stress deformation simulation, a part model of the casting is created, the simulation result of the part model and the simulation result of the process model are compared, the reduced scale, correction and the machining amount are adjusted in real time, and the process model is obtained; manufacturing a process pattern according to the process model, and producing a sand mold by utilizing the process pattern; creating a sand core model, inputting sand mold temperature curve parameters into simulation software, carrying out sand core deformation stress simulation, measuring sand core deformation stress, and manufacturing a core box according to the sand core model; a core bar is manufactured according to the design, the manufactured core bar is placed in a core box, and a sand core is manufactured; demolding the sand core; combining the sand core with the sand mold to obtain a casting cavity; and molten steel is poured into a casting cavity, and a casting blank is formed after cooling and solidification.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature alloy casting technology, and specifically relates to a method for casting large high-temperature alloy blanks with controlled casting dimensions. Background Technology

[0002] In recent years, in order to realize the engineering application of coal-fired power generating units with temperatures of 650℃ and above, China has been carrying out research on high-temperature component materials such as nickel-based and iron-nickel-based materials. For example, new nickel-based and iron-nickel-based alloy materials with Ni ≥ 20wt% are being developed.

[0003] Traditional methods for controlling the dimensions of large iron-based cast steel parts include: 1. Selecting parameters for casting reduction, machining allowance, and compensation based on the process manual; 2. Modifying the process based on actual manufacturing results, designing measures such as anti-deformation allowances and tie rods; 3. Post-processing dimensional deviations through methods such as planing and welding. Therefore, although the dimensional control of traditional cylinder and valve body castings relies heavily on experience, it is still a mature technological process.

[0004] However, compared with traditional iron-based materials, high-temperature alloy materials have the following differences: 1. Significantly different solidification shrinkage, resulting in larger size reduction than traditional iron-based materials; 2. Greater processing difficulty and lower processing efficiency; 3. Larger coefficient of thermal expansion, leading to a higher risk of cracking during hot working and greater difficulty in repair welding. Based on these characteristics, the manufacturing process of components for ultra-supercritical units at 650℃ and above requires even higher dimensional control. Failure to meet dimensional requirements poses a significant risk of scrapping. Currently, there is no effective method to accurately control the dimensions of large high-temperature alloy castings during the casting process. Summary of the Invention

[0005] This invention provides a method for casting large high-temperature alloy blanks to control casting dimensions, thereby solving the technical problem that there is currently no effective method to accurately control the dimensions of large high-temperature alloy castings during the casting process.

[0006] This invention is achieved through the following technical solution: a method for casting large high-temperature alloy blanks with controlled casting dimensions, comprising the following steps:

[0007] S1: Determine the thermophysical parameters of high-temperature alloys;

[0008] S2: Measure the temperature profile of the sand mold after high-temperature alloy casting;

[0009] S3: Create a process model. Use simulation software to simulate the stress and deformation of the casting based on the thermophysical parameters measured in step S1. Simultaneously create a part model of the casting. Compare the simulation results of the part model with those of the process model. Based on the comparison results, adjust the scaling, correction, and machining amount in real time to complete the process model design.

[0010] S4: manufacturing a process pattern according to the designed process model, and detecting the three-dimensional size of the process pattern, and then manufacturing a sand mold by using the manufactured process pattern;

[0011] S5: creating a sand core model, inputting the sand mold temperature curve parameters measured in step S2 into simulation software, developing sand core deformation stress simulation, measuring sand core deformation stress, and manufacturing a core box according to the sand core model;

[0012] S6: designing a core bone according to the stress of the sand core in the molten steel and the stress of the self-weight of the sand core, wherein the safety factor value of the strength in the core bone design process is 1.3-1.5;

[0013] S7: manufacturing a core bone according to the core bone designed in step S6, and placing the manufactured core bone in the core box to manufacture a sand core;

[0014] S8: brushing a coating on the sand core after demolding, and then detecting the sand core and the outer mold in three dimensions to determine that the sand mold size is controlled;

[0015] S9: combining the sand core and the sand mold, detecting the core size, and determining that the core size is controlled to obtain a casting cavity;

[0016] S10: pouring molten steel into the casting cavity, forming a casting blank after the molten steel cools and solidifies, and then detecting the blank size to verify the accuracy of the process design.

[0017] Further, in order to better realize the present application, the large high-temperature alloy blank is a large iron-nickel-based cast steel or a nickel-based cast steel with Ni≥20wt%.

[0018] Further, in order to better realize the present application, the thermal physical parameter values in step S1 include thermal expansion coefficient, solid-liquid phase line, Poisson's ratio, and thermal conductivity coefficient, etc.

[0019] Further, in order to better realize the present application, the method for measuring the temperature curve in step S2 is specifically as follows:

[0020] In the sand mold, a thermocouple is arranged in advance to detect the temperature change of the sand core at a distance of 50-100mm from the surface of the molten steel, and the temperature curve is generated according to the detection result of the thermocouple.

[0021] Further, in order to better realize the present application, the deviation of the manufactured process pattern in step S4 from the process model is within ±1mm.

[0022] Further, in order to better realize the present application, the sand core model created in step S5 is a numerical model used for simulation, and the sand core stress deformation simulation is used to simulate the heat transfer of the sand core after the molten steel is poured into the cavity, the buoyancy of the sand core, and the stress of the sand core during the temperature change of the molten steel.

[0023] Further, in order to better realize the present application, the core bone material in step S7 is carbon steel, which is formed by welding or casting.

[0024] Further, in order to better realize the present application, in step S8, the sand mold is dried at a temperature of 100-180 DEG C, and after drying, three-dimensional detection is performed, and the size deviation is controlled within ±1mm.

[0025] Further, in order to better realize the present application, in step S9, the core size detection is controlled by using a cross-sectional template to detect the wall thickness size and three-dimensional detection to control the core shape size, and the size deviation is controlled within ±2mm.

[0026] Further, in order to better realize the present application, in step S10, the detection of the blank size is performed by using three-dimensional detection means to check the blank size after the box is knocked and the sand is dropped, and before heat treatment, and the accuracy of the verification and process design is specifically that the results of the three-dimensional detection of the blank are compared with the process model to verify the size prediction.

[0027] Compared with the prior art, the present application has the following beneficial effects:

[0028] The large high-temperature alloy blank casting method provided by the present application can effectively control the size of the large high-temperature alloy during the process of being cast into a casting blank, so that the size of the casting obtained is more accurate, and by comparing the three-dimensional detection results of the casting blank with the process model, it can be effectively verified whether the casting blank is consistent with the process model. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to make the technical solutions of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings described below only illustrate some of the embodiments of the present application, and all other embodiments obtained by those of ordinary skill in the art without creative effort based on the embodiments of the present application shall fall within the protection scope of the present application.

[0030] Figure 1 is a flow chart of the method for controlling casting size of a large high-temperature alloy blank provided by the embodiment of the present application. DETAILED DESCRIPTION

[0031] In order to make the technical solutions of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings described below only illustrate some of the embodiments of the present application, and all other embodiments obtained by those of ordinary skill in the art without creative effort based on the embodiments of the present application shall fall within the protection scope of the present application.

[0032] Embodiment 1

[0033] The embodiment provides a method for controlling casting size of a large high-temperature alloy blank, comprising the following steps:

[0034] Step S1: measuring a thermal physical parameter value of the high-temperature alloy.

[0035] The casting simulation software (i.e. magmasoft) needs the thermal physical parameter value of the material for stress deformation simulation of the casting, and the high-temperature alloy is mostly a new type of material, so the thermal physical parameter value is not accurate, and thus needs to be measured to ensure accurate operation of the simulation software. It should be noted that the large high-temperature alloy blank in the embodiment is a large iron-nickel-based cast steel or a nickel-based cast steel with Ni≥20wt%. The thermal physical parameter value includes the thermal expansion coefficient, the solid-liquid phase line, the Poisson's ratio and the thermal conductivity coefficient.

[0036] Step S2: measuring a temperature curve of the sand mold after pouring the high-temperature alloy.

[0037] The casting simulation software needs the temperature curve of the sand mold after pouring the high-temperature alloy for simulating the deformation stress of the sand core and measuring the deformation stress of the sand mold, and the high-temperature alloy is mostly a new type of material, so the temperature curve is not accurate, and thus needs to be measured to ensure accurate operation of the simulation software. In this step, the specific method for measuring the temperature curve is as follows:

[0038] In the sand mold, a thermocouple is arranged in advance to detect the temperature change of the sand core in the range of 50-100 mm from the surface of the molten steel, and a temperature curve is generated according to the detection result of the thermocouple. Specifically, one or more thermocouples are arranged in advance at a position of 50 mm, 60 mm, 70 mm, 80 mm, 90 mm or 100 mm from the surface of the molten steel in the sand mold to measure the temperature curve of the sand mold after the high-temperature alloy is poured.

[0039] Step S3: creating a process model in the casting simulation software, using the simulation software to carry out a simulation of the stress deformation of the casting according to the thermal physical parameter values measured in step S1, synchronously creating a part model of the casting, comparing the part model with the simulation result of the process model, and according to the comparison result, adjusting the scale, correction and machining amount in real time to complete the design of the process model.

[0040] It should be noted that the process model is a model in which the scale, correction and machining amount are added to the part model, that is, the process model and the part model are two different models. By comparing the process model and the part model in the simulation software multiple times and adjusting the size of the process model in real time according to the comparison result, the size of the final process model is more accurate.

[0041] Step S4: producing a process pattern according to the designed process model, and detecting the three-dimensional size of the process pattern, and then producing a sand mold using the produced process pattern.

[0042] In this step, because the size of the process model is very accurate, but there is a manufacturing error in the manufacturing process, it is necessary to detect the three-dimensional size of the produced process pattern and compare the detection result with the process model, so that the deviation of the process pattern compared with the process model is within ±1 mm. Then, the process pattern is used to produce a sand mold, so that the size of the produced sand mold is more accurate.

[0043] Step S5: creating a sand core model (which is a numerical model like the part model and the process model described above) in the simulation software, inputting the sand mold temperature curve parameters measured in step S2 into the simulation software, carrying out a simulation of the deformation stress of the sand core, measuring the deformation stress of the sand core, and manufacturing a core box according to the sand core model.

[0044] In this step, the above-mentioned simulation of the stress deformation of the sand core is a simulation of the heat transfer of the sand core after the molten steel is poured into the mold cavity, the buoyancy condition and the stress condition in the process of temperature change of the molten steel. By adjusting the boundary conditions and heat transfer coefficients in the simulation software data according to the actually measured sand mold temperature drop curve (i.e. the above-mentioned sand mold temperature curve), the degree of coincidence between the simulation result and the actual situation is improved.

[0045] Step S6: According to the stress of the sand core in the molten steel and the stress of the sand core self-weight, the core bone is designed, wherein the safety factor value of the strength in the core bone design process is 1.3-1.5. Specifically, the safety factor value can be 1.3 or 1.4 or 1.5.

[0046] In this step, by using simulation, the relationship between the stress of the sand core under the action of gravity, buoyancy and temperature field in the pouring and solidification process and the tensile strength of the sand core is compared, the thermal deformation of the sand core is predicted, when the deformation of the sand core in each direction is <1mm, the core bone profile parameter is taken, otherwise the parameter of the selected core bone profile needs to be iteratively adjusted.

[0047] Step S7: The core bone is made according to the core bone designed in step S6, and the made core bone is placed in the core box to make the sand core.

[0048] Specifically, according to the core bone designed according to the structure of the casting cavity, the structure of the main core bone is random with the main structure of the sand core, so that it is located in the middle of the sand core. When the sand core is made, the core box is assembled in sections according to the sand striking direction, and the core sand is compacted in turn. The core sand adopts chrome sand, and the strength of the sand core is 0.6-0.8MPa. The core bone material is carbon steel, which is welded or cast into a seamless steel pipe.

[0049] Step S8: The sand core is demolded and coated with paint, and after drying, the sand core and the outer shape are detected three-dimensionally to determine that the sand mold size is controlled.

[0050] In this step, the drying temperature of the sand mold is 100-180℃, for example, 100℃ or 110℃ or 120℃ or 130℃ or 140℃ or 150℃ or 160℃ or 170℃ or 180℃. After drying, three-dimensional detection is performed, and the size deviation is controlled within ±1mm.

[0051] Step S9: The sand core is combined with the sand mold, and the core size is detected to determine that the core size is controlled to obtain the casting cavity. In this step, the core size detection is controlled by using cross-section sample plate detection to control the wall thickness size and three-dimensional detection to control the core shape size, and the size deviation is controlled within ±2mm.

[0052] Step S10: The molten steel is poured into the casting cavity, and after the molten steel cools and solidifies, a casting blank is formed, and then the blank size is detected to verify the accuracy with the process design. In this step, the blank size detection is performed by using three-dimensional detection means to check the blank size after the box is knocked and the sand is dropped, and before heat treatment, to verify the accuracy with the process design. Specifically, the results of the three-dimensional detection of the blank are compared with the process model to verify the size prediction.

[0053] The method carries out simulation verification by determining real simulation boundary conditions. The simulation results of the created part model and process model in the simulation software are compared, and the scale, correction and machining amount are adjusted in real time according to the comparison results, so that the size of the designed process model is more accurate, and the size of the process sample manufactured according to the process model is more accurate. Through size detection of each process, the size of the manufactured sand mold is more accurate, so that the sand core made by the sand mold can obtain a more accurate casting cavity, and based on this, the casting cavity can obtain a more accurate casting blank. Through the method, the size of the large high-temperature alloy during the casting process into a casting blank can be effectively controlled, so that the size of the finally obtained casting is more accurate, and by comparing the three-dimensional detection result of the casting blank with the process model, whether the casting blank is consistent with the process model can be effectively verified. It should be noted that the "large high-temperature alloy blank" refers to a blank made of high-temperature alloy with an outline size of 3-5 meters.

[0054] The above merely provides a specific implementation of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed in the present application, which shall be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method for casting large high-temperature alloy blanks with controlled casting dimensions, characterized in that, Includes the following steps: S1: Determine the thermophysical parameters of high-temperature alloys; S2: Measure the temperature profile of the sand mold after high-temperature alloy casting; S3: Create a process model. Use simulation software to simulate the stress and deformation of the casting based on the thermophysical parameters measured in step S1. Simultaneously create a part model of the casting. Compare the simulation results of the part model with those of the process model. Based on the comparison results, adjust the scaling, correction, and machining amount in real time to complete the process model design. S4: Based on the designed process model, a process pattern is made, and the three-dimensional dimensions of the process pattern are measured. Then, the sand mold is produced using the made process pattern. S5: Create a sand core model, input the sand mold temperature curve parameters measured in step S2 into the simulation software, carry out sand core deformation stress simulation, measure sand core deformation stress, and make a core box according to the sand core model. S6: Design the core frame based on the stress of the sand core in the molten steel and the stress of the sand core's own weight. The safety factor value of the strength of the core frame during the design process is taken as 1.3 to 1.

5. S7: Make the core according to the core design in step S6, and place the made core in the core box to make the sand core; S8: Demold the sand core, apply coating, and after drying, perform three-dimensional inspection of the sand core and its shape to ensure that the sand mold size is under control; S9: Combine the sand core with the sand mold and check the size of the lower core to ensure that the size of the lower core is under control in order to obtain the casting cavity; S10: Molten steel is poured into the casting cavity. After the molten steel cools and solidifies, a casting blank is formed. Then, the dimensions of the blank are checked to verify the accuracy of the process design.

2. The method for casting large high-temperature alloy blanks with controlled casting dimensions according to claim 1, characterized in that: The large high-temperature alloy blank is a large iron-nickel-based cast steel part or a nickel-based cast steel part with Ni ≥ 20wt%.

3. The method for controlling the casting dimensions of large high-temperature alloy blanks according to claim 1, characterized in that: The thermophysical parameters in step S1 include the coefficient of thermal expansion, the solid-liquid phase line, Poisson's ratio, and the thermal conductivity.

4. The method for casting large high-temperature alloy blanks with controlled casting dimensions according to claim 1, characterized in that, The method for measuring the temperature curve in step S2 is as follows: Thermocouples are pre-arranged within a distance of 50-100mm from the surface of the molten steel in the sand mold to detect the temperature change of the sand core, and the temperature curve is generated based on the detection results of the thermocouples.

5. The method for casting large high-temperature alloy blanks with controlled casting dimensions according to claim 1, characterized in that: The deviation between the process pattern produced in step S4 and the process model is within ±1 mm.

6. The method for controlling the casting dimensions of large high-temperature alloy blanks according to claim 1, characterized in that: The sand core model created in step S5 is a numerical model used for simulation. The sand core stress deformation simulation simulates the heat transfer, buoyancy, and stress of the sand core after the molten steel is poured into the cavity.

7. The method for casting large high-temperature alloy blanks with controlled casting dimensions according to claim 1, characterized in that: The core material in step S7 is carbon steel, which is formed by welding or casting seamless steel pipes.

8. The method for casting large high-temperature alloy blanks with controlled casting dimensions according to claim 1, characterized in that: In step S8, the sand mold is dried at a temperature of 100-180℃. After drying, a three-dimensional inspection is performed, and the dimensional deviation is controlled within ±1mm.

9. The method for controlling the casting dimensions of large high-temperature alloy blanks according to claim 1, characterized in that: In step S9, the core size detection is carried out by using a cross-sectional template to detect and control the wall thickness and three-dimensional detection to control the core shape and position, with the size deviation controlled within ±2mm.

10. The method for casting large high-temperature alloy blanks with controlled casting dimensions according to claim 1, characterized in that: In step S10, the blank size is detected by using three-dimensional detection methods after the blank is removed from the mold and before heat treatment. The verification of the accuracy of the process design specifically involves comparing the results of the three-dimensional detection of the blank with the process model to verify the size prediction.

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