CN115213379B - Design method of technological rib of monocrystalline blade regulating flange plate mixed crystal - Google Patents
Design method of technological rib of monocrystalline blade regulating flange plate mixed crystal Download PDFInfo
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- CN115213379B CN115213379B CN202210019504.2A CN202210019504A CN115213379B CN 115213379 B CN115213379 B CN 115213379B CN 202210019504 A CN202210019504 A CN 202210019504A CN 115213379 B CN115213379 B CN 115213379B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D19/00—Casting in, on, or around objects which form part of the product
Abstract
The invention discloses a design method of a process rib of a single crystal blade regulation and control flange plate mixed crystal, belongs to the field of single crystal investment casting processes, and aims to solve the problem of the design of the process rib of the regulation and control flange plate mixed crystal. The method mainly comprises the following steps: (1) determining a critical cooling rate of the platform; (2) determining the adding position of the process rib; (3) determining the adding quantity of the process ribs; (4) determining the structure of the process rib; (5) The drawing rate is improved, and the cooling rate of each point of the edge plate after the process ribs are added is researched; (6) And (3) carrying out actual casting on the blades with and without the added process ribs, and comparing the grain condition at the edge plate. Compared with the prior art, the invention has the advantages that: the process ribs for regulating and controlling the impurity crystals of the flange plate are designed according to the simulated cooling rate.
Description
Technical Field
The invention relates to a casting process of a single crystal casting, in particular to a process rib design method for determining and controlling the impurity crystals of a flange plate by a simulation means.
Background
The single crystal superalloy has excellent high temperature mechanical properties due to the elimination of the influence of grain boundaries. However, as turbine blades become more complex in structure and shape, larger in size, and more defective castings are produced. Among them, the impurity crystal defect at the edge plate is an important problem to be solved in the process of preparing the single crystal blade. The formation mechanism of the mixed crystal is that the local positions have different temperature drop rates due to uneven heat dissipation, so that local supercooling is generated, and the generation of new nuclei is promoted. The presence of the new nuclei creates grain boundaries that disrupt the single crystal integrity of the blade.
The probability of mixed crystal appearance can be reduced by reducing the drawing rate, but the production efficiency is greatly reduced, so that the mode of adding process ribs is adopted at present, solidification of a region with a relatively fast heat dissipation of the flange plate is hindered by adding the heating nodes, the cooling rate of a connecting region is reduced, and mixed crystal control of the region is realized under the condition of improving the drawing rate. Although the regulation and control mode of the process ribs is widely applied, the research on the design method and the addition position of the process ribs is still in a rough and experience-dependent layer, so that the method provides a basis for the design of the process ribs from the simulation angle, and determines the addition position and the design size of the process ribs from the cooling rate angle, so that the effect of the process ribs is exerted as much as possible, and the impurity crystal control of the edge plate area is realized under the condition of improving the drawing rate.
Disclosure of Invention
Aiming at the problem that the single crystal blade is unqualified due to the impurity crystal defect of the edge plate of the turbine blade, the process ribs are added to the edge plate part of the blade, and the traditional process ribs are processed roughly and empirically, therefore, the method provides a simulation-based process rib design method for eliminating the impurity crystal defect of the edge plate, the positions, the numbers and the structures of the added auxiliary process ribs are researched and researched through simulation, the simulation provides basis for design, the verification is carried out through experiments, and finally, the impurity crystal control of the area is realized under the condition of improving the drawing rate.
The technical solution for achieving the above purpose of the present invention comprises the following steps:
And obtaining the critical cooling rate value of the whole edge plate area of the blade of a certain model without generating mixed crystals through early-stage simulation calculation and analysis.
And determining the adding position of the process rib. When the process ribs are added, the short sides comprising the connecting structures are needed to be avoided, and the cooling rate of each point of the edge plate is combined to select the parts which are thicker in size, stronger in deformation resistance and extremely easy to generate miscellaneous crystals for adding the process ribs.
And determining the adding quantity of the process ribs. The cooling rate of each point of the edge plate is changed along with the drawing rate, the principle that the shape and the dimensional accuracy of the edge plate cannot be affected is combined, and meanwhile, the adding position of the process rib is required to be as close to the assembly connection area as possible.
And determining the structure of the process rib. According to the structural characteristics of the flange plate, the structure and the size of the technological rib are designed. Mainly comprises the cross section shape, the cross section size and the extension length of the process rib. The method comprises the following specific steps:
[1] and determining the cross-sectional shape of the process rib. Because the edge of the blade edge plate is thinner and has a rectangular structure, the cross section of the process rib is designed to be rectangular in consideration of operability in the actual production process and easy repairability of the finite element grid.
[2] And determining the cross section width of the process rib. And determining the circulation effect of the molten metal by combining a fine casting process design manual.
[3] And determining the extension length of the technological rib. And comprehensively considering the position and layout of the castings in the furnace body, and determining whether the castings interfere with the furnace body or not.
[4] And determining the cross section length of the process rib. Firstly, the length of the cross section of the process bar is preliminarily valued according to the casting process design manual and the circulation condition of molten metal. Secondly, in order to reduce the influence of the process rib on the deformation of the flange plate, the smaller the dimension selection should be, the better, so that the minimum process rib cross-sectional length is determined through simulation.
And (3) improving the drawing rate, adding the process ribs according to the research result to simulate, and researching the cooling rate distribution of each point of the rear edge plate of the added process ribs.
And (3) carrying out actual casting on the blade with and without the process ribs, and comparing the grain condition at the edge plate.
The beneficial effects of the invention are as follows: the traditional rough type process rib adding and designing modes are avoided, a basis is provided for the design of the process rib, and the adding position and the design size of the process rib are determined from the angle of cooling rate, so that the effect of the process rib is exerted as much as possible, and the impurity crystal control of the edge plate area is realized under the condition of improving the drawing rate.
The invention is further illustrated by the following figures and examples.
Drawings
Fig. 1 is a flow chart of the present invention.
FIG. 2 is a plot of edge plate long side cooling rate measurement point locations.
FIG. 3 is a graph of cooling rates for points on the long edge of the platform.
Fig. 4 is a parameter size diagram of the process tendon structure.
In the figure, the protruding length of the technological rib is A, the cross section length of the technological rib is B, and the cross section width of the technological rib is C.
Fig. 5 is a layout and influence range measurement point diagram of the process tendons.
Fig. 6 is a functional effect diagram of the process tendon.
FIG. 7 is a graph showing the cooling rate distribution of each point on the long side of the flange plate after the addition of the process ribs.
Fig. 8 is a graph of the macro topography at the process tendon addition and no process tendon addition edge plates.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to the attached drawings: the embodiment is implemented on the premise of the technical scheme of the invention, and detailed implementation modes and processes are given. The scope of the invention is not limited to the examples described below.
Taking a certain type of turbine blade as an example, the specific implementation flow of the invention is shown in fig. 1:
The critical cooling rate of no generation of mixed crystals in the whole edge plate area of the blade is 0.74 ℃/s through early simulation calculation analysis.
And determining the adding position of the process rib. Considering that the two short sides of the flange plate comprise a connecting structure and the structure is complex, the possibility of mixed crystals is small when the drawing rate is controlled within a certain range, and therefore, the short side parts comprising the connecting structure are not considered when process ribs are added. Because the thickness of the long edge of the flange plate is thin, structural mutation exists, and mixed crystals are easy to generate when the drawing rate is high, so that the process rib adding mode of the long edge of the flange plate is mainly studied.
Fig. 2 is a position diagram of cooling rate measuring points on the long side of the edge plate, 9 points are sequentially and equidistantly taken on the long side of the leaf basin and the long side of the leaf back edge plate, simulation is carried out by adopting different drawing rates, the cooling rates of the 18 points are measured, and the measurement result is shown in fig. 3. The curve shows that the cooling rate at the point 2 of the leaf basin edge plate and the points 2 and 7 of the leaf back edge plate is larger, measures are needed to control, otherwise, mixed crystals are very easy to generate, so that the process ribs are determined to be added at the points 2 and 7 of the leaf basin edge plate, and meanwhile, the areas are close to the assembly connection area, are thicker in size and have stronger deformation resistance, and the influence of the added process ribs on the shape and size precision of the edge plate can be effectively reduced.
And determining the adding quantity of the process ribs. As can be seen from fig. 3, when the drawing rate exceeds 3mm/min, the mixed crystals appear, and when the drawing rate is 3mm/min, only the point 2 of the blade back edge plate exceeds the critical cooling rate, so that only one process rib needs to be added to control the mixed crystals at the edge plate, but at least three process ribs need to be added to further improve the drawing rate.
And (3) combining the step (2), and finally determining the adding position of the process rib to be the position of the leaf basin edge plate close to the point (2), and the position of the leaf back edge plate close to the point (2) and the point (7).
And determining the structure of the process rib. According to the structural characteristics of the flange plate, the structure and the size of the technological rib are designed. The method mainly comprises the following specific steps of the cross section shape, the cross section size and the extension length of the process rib, as shown in fig. 4:
[1] and determining the cross-sectional shape of the process rib. Because the edge of the blade edge plate is thinner and has a rectangular structure, the cross section of the process rib is designed to be rectangular in consideration of operability in the actual production process and easy repairability of the finite element grid.
[2] And determining the cross section width C of the process rib. And determining that the cross section width of the process rib is 2mm by combining a fine casting process design manual and the circulation effect of molten metal.
[3] The extension A of the technological rib is determined. Considering the layout mode of the leaf basin adopted in the actual casting process of a factory towards the center of the furnace body, the maximum extendable length of the technological rib at the sharp point of the flange plate reaches 3.5mm due to the limitation of the size of the cold copper plate, and the extending length is determined to be 3.5mm in order to avoid interference although a certain gap exists between the cold copper plate and the furnace body in the casting process.
[4] And determining the cross section length B of the process rib. According to the casting process design manual, the length value B of the cross section of the process rib is more than or equal to 4mm according to the casting process design manual and considering the influence of the molten metal circulation effect.
In order to reduce the influence of the process rib on the deformation of the flange plate, the smaller the dimension is, the better the dimension is, so that the minimum process rib cross-section length B is determined by simulation. To investigate the extent of the effect of process ribs of different cross-sectional lengths on the cooling rate, the position of the process ribs was set in the middle of the long edge of the flange as shown in fig. 5. Simulation shows that when B is 5mm, the range of the influence area of the process rib is from point8 to point12, the range of the influence area is 8mm through measurement, and the maximum difference between the cooling rates of the process rib and the cooling rate without the rib is 0.38 ℃/s under the action of the process rib according to the cooling rates of the process rib shown in fig. 6, and the cooling rate values of all areas of the position of the process rib are reduced to be within a critical range by subtracting the difference according to the data research shown in fig. 3. Thus, control of the cooling rate during casting can already be satisfied when b=5 mm.
The drawing rate is increased to 4.5mm/min, other simulation parameters are kept unchanged, and the process ribs are added according to the results obtained by the research to simulate, so that the cooling rate distribution of each point of the rear edge plate of the added process ribs is obtained, as shown in fig. 7, when the drawing rate is 4mm/min compared with fig. 3, the cooling rate of a plurality of points exceeds a critical value, and the process ribs are added according to the design mode of the invention, so that the cooling rate of a process rib connection area and a certain range around the process ribs is reduced when the drawing rate is 4.5mm/min, and the points of all areas are under the critical cooling rate, which indicates that the control of mixed crystals is effectively realized based on the mode of adding process ribs of an auxiliary structure.
The actual pouring is carried out on the blade with and without the process ribs provided by the invention when the drawing speed is 4.5mm/min, and the situation of the crystal grains at the position of the blade is compared, as shown in figure 8, according to the macroscopic appearance diagram, the blade edge plate without the process ribs has obvious mixed crystals, and the mixed crystals of the blade edge plate with the process ribs are eliminated. Therefore, the method for determining the design size and the arrangement position of the process ribs through simulation is feasible.
Claims (1)
1. The design method of the technological rib of the monocrystalline blade regulation and control edge plate mixed crystal is characterized by comprising the following steps:
step 1
And obtaining the critical cooling rate value of the whole edge plate area of the blade of a certain model without generating mixed crystals through early-stage simulation calculation and analysis.
Step 2
And determining the adding position of the process rib. When the process ribs are added, the short sides comprising the connecting structures are needed to be avoided, and the cooling rate of each point of the edge plate is combined to select the parts which are thicker in size, stronger in deformation resistance and extremely easy to generate miscellaneous crystals for adding the process ribs.
Step 3
And determining the adding quantity of the process ribs. The cooling rate of each point of the edge plate is changed along with the drawing rate, the principle that the shape and the dimensional accuracy of the edge plate cannot be affected is combined, and meanwhile, the adding position of the process rib is required to be as close to the assembly connection area as possible.
Step 4
And determining the structure of the process rib. According to the structural characteristics of the flange plate, the structure and the size of the technological rib are designed. Mainly comprises the cross section shape, the cross section size and the extension length of the process rib. The method comprises the following specific steps:
[1] and determining the cross-sectional shape of the process rib. Because the edge of the blade edge plate is thinner and has a rectangular structure, the cross section of the process rib is designed to be rectangular in consideration of operability in the actual production process and easy repairability of the finite element grid.
[2] And determining the cross section width of the process rib. And determining the circulation effect of the molten metal by combining a fine casting process design manual.
[3] And determining the extension length of the technological rib. And comprehensively considering the position and layout of the castings in the furnace body, and determining whether the castings interfere with the furnace body or not.
[4] And determining the cross section length of the process rib. Firstly, the length of the cross section of the process bar is preliminarily valued according to the casting process design manual and the circulation condition of molten metal. Secondly, in order to reduce the influence of the process rib on the deformation of the flange plate, the smaller the dimension selection should be, the better, so that the minimum process rib cross-sectional length is determined through simulation.
Step 5
And (3) improving the drawing rate, adding the process ribs according to the research result to simulate, and researching the cooling rate distribution of each point of the rear edge plate of the added process ribs.
Step 6
And (3) carrying out actual casting on the blade with and without the process ribs, and comparing the grain condition at the edge plate.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19963349A1 (en) * | 1999-12-27 | 2001-06-28 | Abb Alstom Power Ch Ag | Blade for gas turbines with throttle cross section at the rear edge |
| CN204321097U (en) * | 2014-11-14 | 2015-05-13 | 西北工业大学 | Hot investment casting single crystal turbine blade model process bar |
| CN110252958A (en) * | 2019-06-21 | 2019-09-20 | 西安交通大学 | It is a kind of based on listrium it is hollow/porous structure inhibit listrium stray crystal defect blade casting mold preparation method |
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- 2022-01-10 CN CN202210019504.2A patent/CN115213379B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19963349A1 (en) * | 1999-12-27 | 2001-06-28 | Abb Alstom Power Ch Ag | Blade for gas turbines with throttle cross section at the rear edge |
| CN204321097U (en) * | 2014-11-14 | 2015-05-13 | 西北工业大学 | Hot investment casting single crystal turbine blade model process bar |
| CN110252958A (en) * | 2019-06-21 | 2019-09-20 | 西安交通大学 | It is a kind of based on listrium it is hollow/porous structure inhibit listrium stray crystal defect blade casting mold preparation method |
Non-Patent Citations (1)
| Title |
|---|
| 工艺条件对镍基高温合金DD483单晶叶片中杂晶缺陷的影响;马德新;张琼元;王海洋;王海伟;赵代银;张松泉;李林蓄;刘俊;贺群功;巩秀芳;杨功显;;铸造(05);第439-444页 * |
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