Device for testing forming quality of pressure-regulating cast high-temperature alloy thin wall

Abstract

The invention relates to the field of pouring molds, and particularly discloses a pressure-regulating cast high-temperature alloy thin-wall forming quality testing device which comprises a forming structure with an upper portion, a middle portion and a lower portion integrally formed, and the upper portion forming structure and the lower portion forming structure are each provided with a plurality of testing hollow plates with different thicknesses; wherein the test hollow plate which is vertically arranged relative to the middle forming structure is connected to the upper forming structure; wherein the test hollow plate which is transversely arranged relative to the middle forming structure is connected to the lower forming structure; the middle forming structures are at least two spiral line alloy flowing structures with different wall thicknesses, thin-wall plate-shaped samples with different wall thicknesses, variable-cross-section plate-shaped samples with different thicknesses and spiral line samples with different wall thicknesses are arranged on a pouring system based on a bottom pouring mode and a side pouring mode; and flexible combination of high-throughput sample preparation arrays can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of casting moulds, in particular to a testing mould for pressure-regulated casting of high-temperature alloy thin-wall forming quality. Background Art

[0002] In order to improve the overall performance, achieve structural weight reduction and high reliability, aircraft engines are increasingly using parts with complex thin-walled characteristic structures. Among them, typical castings represented by casings are developing towards large size, complex structure and thin-walled lightweight, which leads to the lower and lower forming quality of high-temperature alloy castings produced by traditional gravity casting. Therefore, it is urgent to seek new casting technologies to improve the forming quality of large thin-walled castings such as casings. At this time, pressure-regulated casting comes into people's attention. Compared with conventional gravity casting, pressure-regulated casting fills and solidifies under pressure. In theory, it has stronger filling capacity and shrinkage compensation capacity than conventional gravity casting, which makes it greatly improve the forming quality of investment casting.

[0003] At present, high-temperature alloy pressure-regulated casting is still in its early stages of development. The influence of pressure-regulated casting process parameters on its filling capacity, shrinkage compensation capacity and casting performance is still unclear, and the equipment is expensive. It is extremely important to predict the filling capacity and shrinkage compensation capacity of high-temperature alloy thin-walled castings in advance, based on which the selection of boosting process parameters and the structural design of the engine can be carried out. Therefore, how to fully demonstrate the forming quality of pressure-regulated casting through an efficient and reliable characterization method with a limited number of experiments has become a top priority.

[0004] So far, the industry usually uses fluidity to evaluate the forming quality of high-temperature alloys, believing that good alloy fluidity is conducive to the filling and shrinkage compensation of the alloy melt, but it does not take into account the influence of the height, width and variable cross-section of the thin wall on the forming quality of the casting, which is obviously incomplete; and the commonly used test models so far are often for conventional gravity casting, and test models for pressure-regulated casting are rare.

[0005] Chinese patent CN 114279802 A discloses a high-temperature alloy fluidity test mold and a method for preparing a test sample. Although the model proposed in the patent is small in size and can be used to test the fluidity of high-temperature alloys in a vacuum furnace, it is only applicable to gravity casting and is not applicable to pressure-regulated casting. Secondly, it requires many process tests, large errors, and high experimental costs. The overall weight of the poured alloy liquid has a significant impact on the structure, and the variable cross-section effect and large size effect of the casting are not taken into account.

[0006] Chinese patent CN 117761276 A discloses a high-throughput experimental system for characterizing the casting process performance of high-temperature titanium-based alloys and its preparation method. Although this patent can characterize the casting process performance of titanium-based alloys with different wall thicknesses under gravity casting, it does not take into account the influence of variable cross-section on forming quality, nor does it take into account the influence of different casting technologies and different filling methods on forming quality.

[0007] At present, high-temperature alloy pressure-regulated casting is still in its early stages of development. The effects of pressure-regulated casting process parameters on its filling capacity, shrinkage compensation capacity and casting performance are still unclear, and the equipment is expensive to use. However, it is extremely important to predict the filling capacity and shrinkage compensation capacity of high-temperature alloy thin-walled castings in advance, based on which the selection of boosting process parameters and the structural design of the engine can be carried out. Therefore, how to fully demonstrate the forming quality of pressure-regulated casting through an efficient and reliable characterization method with a limited number of experiments has become a top priority. Summary of the invention

[0008] The purpose of the present invention is to provide a test mold for the thin-wall forming quality of high-temperature alloy pressure-regulated casting. In view of the problem that the thin-wall forming quality of high-temperature alloy pressure-regulated casting is difficult to accurately evaluate, the advantages of pressure-regulated casting are adopted. Based on bottom-pouring and side-pouring filling methods, experiments are carried out on samples with different wall thicknesses, different variable cross-sections and different assembly sequences to achieve high-throughput testing of forming quality; and through spiral wire samples, the ultimate filling capacity of pressure-regulated casting is characterized; the manufacturing cost and R&D time are reduced to solve the problems raised in the above-mentioned background technology.

[0009] To achieve the above object, the present invention provides the following technical solutions: a test die for the forming quality of thin-walled high-temperature alloys cast by pressure regulation, comprising a forming structure in which the upper, middle and lower parts are integrally formed; The upper forming structure includes a cross connecting frame and a plurality of test hollow plates, and the plurality of test hollow plates are vertically connected to the top surface of the cross connecting frame; The center of the cross connecting frame is connected with a hollow cylinder; The cross connecting frame is connected to a hollow cylinder on one side facing away from the upper forming structure; The lower forming structure also includes a plurality of test hollow plates, and the plurality of test hollow plates are transversely connected to the hollow cylinder; A middle forming structure is provided between the upper forming structure and the lower forming structure; The middle forming structure comprises at least two spiral wire alloy flow structures with different wall thicknesses, and the hollow cylinder penetrates through and communicates with the two spiral wire alloy flow structures.

[0010] Preferably, the test hollow plate is composed of a large-section plate body and a small-section plate body, and the test hollow plate has different thicknesses.

[0011] The two spiral wire alloy flow structures have wall thicknesses of 2 mm and 4 mm respectively, wherein the thin spiral wire alloy flow structure is sleeved on the thick spiral wire alloy flow structure.

[0012] Preferably, the casting form of the upper molding structure includes bottom pouring.

[0013] Preferably, the casting form of the lower molding structure includes side injection.

[0014] Preferably, the upper molding structure is used to characterize the influence of side-pouring filling under pressure-regulated casting on the molding quality of the casting, the middle molding structure is used to characterize the ultimate filling capacity of different wall thicknesses under pressure-regulated casting, and the lower molding structure is filled gradually from bottom to top to characterize the influence of bottom-pouring filling under pressure-regulated casting on the molding quality of the casting.

[0015] The present invention has at least the following beneficial effects: 1. The present invention has different effects on the forming quality of castings with the changes of pouring sequence, single thin wall thickness, variable cross-section size and variable cross-section installation sequence. Here, the filling capacity, grain size, shrinkage and shrinkage cavity, dendrite growth mode, segregation, precipitation phase and performance at different positions can be measured according to the formed castings. The number of experiments and the influence of objective experimental factors are reduced, and the multi-faceted experimental verification of the forming quality of pressure-regulated castings is realized; 2. The present invention is based on bottom pouring and side pouring, and thin-walled plate samples with different wall thicknesses, variable-section plate samples with different thicknesses, and spiral wire samples with different wall thicknesses are arranged on the pouring system, so as to realize the flexible combination of sample high-throughput preparation array. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall three-dimensional structure of the present invention; Figure 2 It is a schematic diagram of the overall top view structure of the present invention; Figure 3 It is a schematic diagram of the overall side structure of the characteristics of the present invention; Figure 4 It is a schematic diagram of the thickness dimension of the hollow plate tested in the upper forming structure of the present invention; Figure 5 It is a schematic diagram of the connection structure between the spiral wire alloy flow structure and the hollow cylinder in the present invention; Figure 6 It is a schematic diagram of the connection structure of the test hollow plate and the hollow cylinder in the lower molding structure of the present invention; Figure 7It is a schematic diagram of the integrated molding structure and the pressure regulating device used in conjunction with each other in the present invention; Figure 8 It is a schematic diagram of the connection between the hollow cylinder and the cross connecting frame of the present invention.

[0017] In the attached figure: 1. test hollow plate; 2. hollow cylinder; 3. cross connecting frame. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Embodiment 1 See also Figure 1 - Figure 8 The present invention provides a testing device for the forming quality of thin-walled high-temperature alloys by pressure-regulated casting, specifically a testing mold for the forming quality of thin-walled high-temperature alloys by pressure-regulated casting, including a sprue, a cross runner, thin walls with different wall thicknesses, variable cross-sections of different sizes, and a spiral flow channel. It is worth noting that for the same casting technology, different filling methods have a great influence on the forming quality of the casting. A sprue nest is provided at the top of the sprue, and the side injection method is used to fill the plate-like thin-walled casting at the bottom of the sprue to characterize the influence of the side injection method on the forming quality of the casting under pressure-regulated casting; a spiral alloy flow specimen with different wall thicknesses is provided in the middle to characterize the limit filling capacity of different wall thicknesses under pressure-regulated casting; the top part adopts the bottom injection method to fill the plate-like thin-walled casting step by step from bottom to top to characterize the influence of the bottom injection method on the forming quality of the casting under pressure-regulated casting.

[0020] Specifically, when testing, this structure is combined with a voltage regulating device (such as Figure 7 ), an opening connected to the pressure regulating device is provided at the bottom of the hollow cylinder 2. In this scheme, the molten metal is injected from the bottom of the device by means of pressure regulation, which is pressure-regulated casting.

[0021] First, the molten metal enters the lower molding structure through the hollow cylinder 2. The lower molding structure is provided with a plurality of test hollow plates 1. The test hollow plates 1 are connected to the hollow cylinder 2 in the transverse direction and are evenly distributed in the circumferential direction of the hollow cylinder 2. In this way, the molten metal enters the test hollow plates 1 in a side injection manner. Secondly, enter the middle forming structure, which is two spiral wire alloy flow samples with different wall thicknesses. The two spiral wire alloy flow samples with different wall thicknesses are connected to the hollow cylinder 2, wherein the thinner spiral wire alloy flow sample is sleeved on the thicker spiral wire alloy flow sample, so that the molten metal enters the two spiral wire alloy flow samples; Finally, it enters the upper forming structure, which is composed of several test hollow plates 1 and a cross connecting frame 3. One end of the hollow cylinder 2 is connected to the cross connecting frame 3. Several test hollow plates 1 are vertically connected to the cross connecting frame 3. The molten metal enters the several vertically arranged test hollow plates 1 from below.

[0022] The present invention adopts an integrally formed structure and can simultaneously measure the filling capacity, grain size, shrinkage and shrinkage cavities, dendrite growth mode, segregation, precipitation phase, and performance at different positions of the formed castings through one device, thereby reducing the number of experiments and the influence of objective experimental factors, and realizing multi-faceted experimental verification of the forming quality of pressure-regulated castings.

[0023] The present invention can test the upper, middle and lower forming structures at one time through the same channel injection, saving a lot of time, and the objects of the tests of the three forming structures of the upper, middle and lower forming structures are different, and each forming structure tests specific different forming structures respectively; For example, the upper part can test the vertically arranged test hollow plates 1 of different sizes, the middle part can test the spiral wire alloy flow specimens of different sizes, and the lower part can test the horizontally arranged test hollow plates 1 of different sizes. At the same time, different injection methods are also tested, such as the influence of bottom injection and side injection on the test hollow plate 1. This scheme solves the casting defects such as undercasting and cold shut under pressure-regulated casting by selecting the wall thickness of the middle molding structure.

[0024] As a further illustration of the present invention, during the filling process of the alloy liquid, the resistance brought by the casting structure is mainly friction resistance and surface tension. Surface tension is the result of the attraction of molecules in the fluid. It is a property of the substance itself and is related to the temperature and the material properties between the phase interfaces. When dealing with the flow process between thin walls, the additional pressure caused by surface tension must be considered. For thin-walled castings, the Fr criterion is a secondary criterion and the We criterion is a primary criterion. Therefore, the wall thickness corresponding to We / Fr=1 can be called the critical wall thickness.

[0025] In the formula, is the critical wall thickness, is the alloy surface tension, is the density, is the acceleration due to gravity.

[0026] The values ​​of each item for high temperature alloys are: , , , then we get: That is, for nickel-based high-temperature alloys, as long as the wall thickness is less than about 4.6mm, it is a thin-walled casting. And the filling capacity of the casting is greatly improved under pressure-regulated casting. Therefore, according to the critical wall thickness of high-temperature alloy thin-walled castings and the structure of casing castings, the wall thickness of single thin-walled plate castings is 1mm, 2mm, and 3mm respectively. For the load-bearing thick wall thickness, 5mm, 7.5mm, 10mm and 15mm are selected.

[0027] Among them, it is worth further explaining that the filling capacity of pressure-regulated casting is greatly improved compared with gravity casting.

[0028] After a lot of experimental studies on pressure-regulated casting, it was found that when the wall thickness is 1mm, it is extremely difficult to fill the thin wall due to its own structural effect, while when the wall thickness is greater than 5mm, casting defects such as undercasting and cold shut usually do not occur under pressure-regulated casting. Therefore, the wall thickness of the mid-end spiral line is selected to be 2mm and 4mm.

[0029] For variable cross-sectional sizes, according to Bernoulli's principle, assuming that the molten metal is non-viscous, incompressible and stable, the variable cross-sectional area satisfies Bernoulli's principle. After entering the small cross-sectional area, the velocity increases and the pressure decreases.

[0030] Then, by combining the Bernoulli law and the law of conservation of momentum under pressure-regulated casting, the law of velocity change of the molten metal after it flows into the small cross-section of the contraction structure can be expressed as: in, Indicates the height of the molten metal rising in a small cross section. Indicates the filling time; represents the cross-sectional area of ​​the riser; Indicates the cross-sectional area of ​​the cavity. represents the cross-sectional area of ​​the crucible; represents the head loss coefficient along the way; Indicates the diameter of the riser pipe; Indicates the density of the molten metal; represents the acceleration due to gravity; Indicates the initial depth of the riser tube buried in the molten metal in the crucible; It indicates the depth of the riser tube buried in the molten metal in the crucible when flowing through a small cross section; represents the surface tension coefficient; represents the contact angle; Indicates the pressure at the bottom of the small cross-section of the contraction structure.

[0031] The moment the molten metal flows into the small cross-section, the momentum is conserved. Under the action of pressure, the molten metal rises to the position of the straight contraction structure, which will be blocked by the mold shell. Part of the energy is lost (the energy loss increases as the cross-sectional ratio decreases), and the other part of the momentum is released at the small cross-section. The speed of the molten metal in the small cross-section cavity increases rapidly. It is worth noting that when the pressurization speed is low, the molten metal fills the small cross-sectional thin-walled area over a large area due to inertia, and then cannot get subsequent pressure support and begins to fall back, making secondary filling more difficult. Moreover, the size of the variable cross-section structure will greatly affect the occurrence of this phenomenon. Therefore, based on the relevant dimensions of casing castings and the influence of the variable cross-section size on the forming quality, the variable cross-section ratio is selected here.

[0032] They are 5:1, 5:2, 5:3, 7.5:1, 7.5:2, 7.5:3, 10:1, 10:2, 10:3, 15:1, 15:2, and 15:3 respectively.

[0033] In this way, by selecting different cross-sectional ratios during testing, the influence of relevant dimensions and variable cross-sectional dimensions on the forming quality can be explored at once.

[0034] In addition, large thin-walled castings such as casings have upper and lower flange structures, so the installation order of the variable-section components is changed from a sudden contraction structure to a sudden expansion structure, which is more in line with the structure of the actual casting. However, this will cause changes in the filling and shrinkage compensation of the pouring system, and will also greatly change its forming quality. At this time, by setting different variable section sizes, the best tolerance is explored. Specifically: 1:15, 2:15, 3:15, 4:15, 5:15, 6:15.

[0035] For example, on the transverse line of the cross-connected frame 3, a test hollow plate 1 with a ratio of 15:1 is set, followed by a test hollow plate 1 with a ratio of 15:2, followed by a test hollow plate 1 with a ratio of 15:3, and so on. This arrangement does not follow a fixed arrangement order, and the upper forming structure needs to set each ratio to; In the lower molding structure, for example, in the circumferential direction of the hollow cylinder 2, no less than 8 test hollow plates 1 with different cross-sectional ratios are selected from the above cross-sectional ratios for testing.

[0036] As a further illustration of the present invention, based on the bottom pouring and side pouring methods, thin-walled plate samples with different wall thicknesses, variable-section plate samples with different thicknesses, and spiral wire samples with different wall thicknesses are arranged on the pouring system, so as to realize a flexible combination of high-throughput preparation arrays of samples.

[0037] As a further illustration of the present invention, the changes in the pouring sequence, the thickness of a single thin wall, the size of a variable cross section, and the sequence of the installation of a variable cross section have different effects on the forming quality of the casting. Here, the filling capacity, grain size, shrinkage and shrinkage cavity, dendrite growth mode, segregation, precipitation phase, and performance at different positions of the formed casting can be measured. The number of experiments and the influence of objective experimental factors are reduced, and a multi-faceted experimental verification of the forming quality of the pressure-regulated casting is achieved.

[0038] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0039] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that many changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the invention.

Claims

1. A test die for the forming quality of high-temperature alloy thin-wall casting by pressure regulation, characterized in that: It includes an upper molding structure, a middle molding structure and a lower molding structure, and the above molding structures are all integrally formed; The upper forming structure comprises a cross connecting frame (3) and a plurality of test hollow plates (1), wherein the plurality of test hollow plates (1) are vertically connected to the top surface of the cross connecting frame (3); The cross connecting frame (3) is connected to a hollow cylinder (2) on a side facing away from the upper forming structure; One end of the hollow cylinder (2) away from the cross connecting frame (3) is connected to the lower forming structure; The lower forming structure also comprises a plurality of test hollow plates (1), wherein the plurality of test hollow plates (1) are laterally connected to the hollow cylinder (2); A middle forming structure is provided between the upper forming structure and the lower forming structure; The middle forming structure comprises at least two spiral wire alloy flow structures with different wall thicknesses, and the hollow cylinder (2) penetrates through and is connected to the two spiral wire alloy flow structures.

2. A test mold for the forming quality of high-temperature alloy thin-wall casting by pressure regulation according to claim 1, characterized in that: The test hollow plate (1) is composed of a large-section plate body and a small-section plate body, and the test hollow plate (1) has different thicknesses.

3. A test mold for the forming quality of high-temperature alloy thin-wall casting by pressure regulation according to claim 1, characterized in that: The two spiral wire alloy flow structures have wall thicknesses of 2 mm and 4 mm respectively, wherein the thin spiral wire alloy flow structure is sleeved on the thick spiral wire alloy flow structure.

4. A test mold for the forming quality of high-temperature alloy thin-wall casting by pressure regulation according to claim 1, characterized in that: The casting form of the upper molding structure includes bottom pouring.

5. The test mold for the forming quality of high-temperature alloy thin-wall casting by pressure regulation according to claim 1, characterized in that: The casting form of the lower molding structure includes side injection.

6. A test mold for the forming quality of high-temperature alloy thin-wall casting by pressure regulation according to claim 1, characterized in that: The upper molding structure is used to characterize the influence of side-pouring filling under pressure-regulated casting on the molding quality of castings, the middle molding structure is used to characterize the ultimate filling capacity of different wall thicknesses under pressure-regulated casting, and the lower molding structure is filled gradually from bottom to top to characterize the influence of bottom-pouring filling under pressure-regulated casting on the molding quality of castings.

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