A testing device for the forming quality of thin-walled superalloy in pressure regulating casting

Abstract

The present invention relates to the field of casting molds, and specifically discloses a test device for the forming quality of thin-walled high-temperature alloys in pressure-regulated casting, which includes a forming structure integrally formed by an upper part, a middle part, and a lower part. A number of test hollow plates with different thicknesses are provided on both the upper and lower forming structures. Among them, the test hollow plates vertically arranged relative to the middle forming structure are connected to the upper forming structure. Among them, the test hollow plates horizontally arranged relative to the middle forming structure are connected to the lower forming structure. The middle forming structure is at least a spiral alloy flow structure with two different wall thicknesses. Based on bottom gating and side gating, the present invention sets thin-walled plate-shaped specimens with different wall thicknesses, variable cross-section plate-shaped specimens with different thicknesses, and spiral specimens with different wall thicknesses in the gating system, and can realize the flexible combination of high-throughput preparation arrays of specimens.

Description

Technical Field

[0001] The present invention relates to the technical field of casting molds, and particularly to a test mold for testing the forming quality of high-temperature alloy thin-walled parts in pressure-regulated casting. Background Technique

[0002] In order to improve its overall performance, achieve structural weight reduction and high reliability, aero-engines increasingly use components with complex thin-walled characteristic structures. Among them, typical castings represented by casings are developing towards larger sizes, more complex structures and thinner-wall lightweighting, which leads to a decreasing forming quality of high-temperature alloy castings produced by traditional gravity casting. Therefore, there is an urgent need to seek new casting technologies to improve the forming quality of large thin-walled casings. At this time, pressure-regulated casting comes into people's view. Compared with conventional gravity casting, pressure-regulated casting fills and solidifies under pressure, and theoretically has stronger filling ability and feeding ability than conventional gravity casting, which enables it to greatly improve the forming quality of investment casting.

[0003] At present, the pressure-regulated casting of high-temperature alloys still belongs to the initial stage of development so far. The influence of pressure-regulated casting process parameters on its filling ability, feeding ability and casting performance is still unclear, and the equipment usage cost is relatively high. It is extremely important to predict in advance the filling ability and feeding ability of high-temperature alloy thin-walled castings. Based on this, the selection of pressure-increasing 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 the top priority.

[0004] So far, the industry usually evaluates the forming quality of high-temperature alloys by fluidity, believing that good alloy fluidity is beneficial to the filling and feeding of alloy melts, but it does not consider the influence of the height, width and variable cross-section of thin walls on the forming quality of castings, which is obviously incomplete; and the commonly used test models so far are often for conventional gravity casting, and there are few test models for pressure-regulated casting.

[0005] Chinese Patent CN 114279802 A discloses a method for preparing a high-temperature alloy fluidity test mold and test specimens. Although the model proposed in this patent is small in volume and can realize the test of high-temperature alloy fluidity in a vacuum furnace, first, it is only applicable to gravity casting and not applicable to pressure-regulated casting; second, it requires many process testings, has large errors, high experimental costs, the overall weight of the poured alloy liquid has a significant impact on the structure, and does not consider the variable cross-section effect and large-size effect of castings.

[0006] Chinese Patent CN 117761276 A discloses a high-throughput experimental system for characterizing the casting process performance of superalloy 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 consider the influence of variable cross-sections on the forming quality, nor does it consider the influence of different casting techniques and different filling methods on the forming quality.

[0007] Currently, the pressure-regulated casting of superalloys is still in the initial stage of development. The influence of pressure-regulated casting process parameters on its filling ability, feeding ability, and casting performance is still unclear, and the equipment usage cost is relatively high. For superalloy thin-walled castings, it is extremely important to predict the filling ability and feeding ability in advance. Based on this, 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 the top priority. Summary of the Invention

[0008] The purpose of the present invention is to provide a test mold for the forming quality of superalloy thin-walled parts by pressure-regulated casting. Aiming at the problem that it is difficult to accurately evaluate the forming quality of superalloy thin-walled parts by pressure-regulated casting, fitting the advantages of pressure-regulated casting, based on the bottom-gating and side-gating filling methods, experiments are carried out on specimens with different wall thicknesses, different variable cross-sections, and different assembly sequences to achieve high-throughput testing of the forming quality; and through spiral specimens, the ultimate filling ability of pressure-regulated casting is characterized; the manufacturing cost and R & D time are reduced to solve the problems raised in the above background technology.

[0009] To achieve the above purpose, the present invention provides the following technical solution: A test mold for the forming quality of superalloy thin-walled parts by pressure-regulated casting, including a forming structure integrally formed by an upper part, a middle part, and a lower part;

[0010] The upper forming structure includes a cross-shaped 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-shaped connecting frame;

[0011] A hollow cylinder is connected to the center of the cross-shaped connecting frame;

[0012] A hollow cylinder is connected to the side of the cross-shaped connecting frame facing away from the upper forming structure;

[0013] The lower forming structure also includes a plurality of test hollow plates, and the plurality of test hollow plates are horizontally connected to the hollow cylinder;

[0014] A middle forming structure is arranged between the upper forming structure and the lower forming structure;

[0015] The middle forming structure includes spiral alloy flow structures with at least two different wall thicknesses, and the hollow cylinder penetrates through the two spiral alloy flow structures and is connected;

[0016] The two spiral alloy flow structures have wall thicknesses of 2 mm and 4 mm respectively, and the thin spiral alloy flow structure is sleeved on the thick spiral alloy flow structure.

[0017] Preferably, the test hollow plate is composed of a large cross-section plate body and a small cross-section plate body, and the test hollow plate has different thicknesses.

[0018] Preferably, the pouring form of the upper forming structure includes bottom pouring.

[0019] Preferably, the pouring form of the lower forming structure includes side pouring.

[0020] Preferably, the upper forming structure is used to characterize the influence of bottom pouring filling under adjusted-pressure casting on the forming quality of castings, the middle forming structure is used to characterize the ultimate filling ability with different wall thicknesses under adjusted-pressure casting, and the lower forming structure is filled step by step from bottom to top to characterize the influence of side pouring filling under adjusted-pressure casting on the forming quality of castings.

[0021] The present invention has at least the following beneficial effects:

[0022] 1. With the changes in the pouring sequence, single thin-wall thickness, variable cross-section size, and variable cross-section installation sequence of the present invention, different influences are brought to the forming quality of castings. Here, the filling ability, grain size, shrinkage porosity, dendrite growth mode, segregation, precipitation phase, and properties at different positions of the formed castings can be measured. The number of experiments and the influence of experimental objective factors are reduced, and multi-faceted experimental verification of the forming quality of adjusted-pressure casting castings is realized;

[0023] 2. Based on bottom pouring and side pouring, thin-wall plate-shaped specimens with different wall thicknesses, variable cross-section plate-shaped specimens with different thicknesses, and spiral specimens with different wall thicknesses are set in the gating system of the present invention, and flexible combination of a high-throughput preparation array of specimens can be achieved. Description of the Drawings

[0024] Figure 1 It is a schematic three-dimensional structure diagram of the whole of the present invention;

[0025] Figure 2 It is a schematic top view structure diagram of the whole of the present invention;

[0026] Figure 3 It is a schematic side view structure diagram of the whole feature of the present invention;

[0027] Figure 4 It is a schematic diagram of the thickness dimension of the test hollow plate in the upper forming structure of the present invention;

[0028] Figure 5 Schematic diagram of the connection structure between the spiral alloy flow structure and the hollow cylinder in the present invention;

[0029] Figure 6 Schematic diagram of the connection structure between the test hollow plate and the hollow cylinder in the lower molding structure of the present invention;

[0030] Figure 7 Schematic diagram of the cooperation between the molding structure of the integral molding of the present invention and the pressure regulating equipment;

[0031] Figure 8 Schematic diagram of the connection between the hollow cylinder and the cross-connecting frame of the present invention.

[0032] In the drawings: 1. Test hollow plate; 2. Hollow cylinder; 3. Cross-connecting frame. Specific embodiments

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0034] Embodiment 1

[0035] Please refer to Figure 1 - Figure 8 , the present invention provides a test device for the forming quality of thin-walled high-temperature alloys in pressure-regulated casting, specifically a test mold for the forming quality of thin-walled high-temperature alloys in pressure-regulated casting, including a sprue, a runner, thin walls with different wall thicknesses, variable cross-sections with different sizes, and a spiral flow channel. It should be noted that for the same casting technology, different filling methods have a great impact on the forming quality of the casting. A sprue well is provided at the top of the sprue. The side-injection method is used at the lower part of the sprue to fill the plate-shaped thin-walled casting to characterize the influence of side-injection filling under pressure-regulated casting on the forming quality of the casting; spiral alloy flow specimens with different wall thicknesses are provided in the middle to characterize the ultimate filling ability of different wall thicknesses under pressure-regulated casting; the bottom-injection method is used at the upper part to fill the plate-shaped thin-walled casting step by step from bottom to top to characterize the influence of bottom-injection filling under pressure-regulated casting on the forming quality of the casting.

[0036] Specifically, when conducting the test, this structure is combined with a pressure regulating device (such as Figure 7 ), an opening communicating with the pressure regulating device is provided at the bottom of the hollow cylinder 2. In this solution, the molten metal is injected from the bottom of the device by means of pressure regulation, which is pressure-regulated casting.

[0037] First, the molten metal enters the lower forming structure through the hollow cylinder 2. The lower forming structure is provided with several test hollow plates 1. The test hollow plates 1 are horizontally connected to the hollow cylinder 2 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;

[0038] Secondly, it enters the middle forming structure. The middle forming structure is two spiral alloy flow specimens with different wall thicknesses. The two spiral alloy flow specimens with different sizes and wall thicknesses are connected to the hollow cylinder 2. The thinner spiral alloy flow specimen is sleeved on the thicker spiral alloy flow specimen. In this way, the molten metal enters the two spiral alloy flow specimens;

[0039] Finally, it enters the upper forming structure. The upper forming structure 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, and 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.

[0040] Through the integrally formed structure of the present invention, with one device, it is possible to simultaneously measure the filling ability, grain size, porosity, dendrite growth mode, segregation, precipitation phase, and properties at different positions of the formed casting, reducing the number of experiments and the influence of experimental objective factors, and realizing the multi-faceted experimental verification of the forming quality of the pressure-regulating casting.

[0041] Through the same channel injection, the present invention can test the upper, middle, and lower forming structures at one time, saving a lot of time. Moreover, the test objects of the three forming structures of the upper, middle, and lower parts are different, and each forming structure respectively tests specific different forming structures;

[0042] For example, the upper part can test the test hollow plates 1 vertically arranged with different sizes, the middle part can test the spiral alloy flow specimens with different sizes, and the lower part can test the test hollow plates 1 horizontally arranged with different sizes. At the same time, it also tests the influence of different injection methods, such as bottom injection and side injection, on the test hollow plates 1. This solution solves the casting defects such as undercasting and cold shut that occur under pressure-regulating casting by selecting the wall thickness of the middle forming structure.

[0043] 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.

[0044]

[0045] In the formula, is the critical wall thickness, is the alloy surface tension, is the density, is the acceleration due to gravity.

[0046] The values ​​of each item for high temperature alloys are: , , , then we get:

[0047]

[0048] 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.

[0049] Among them, it is worth further explaining that the filling capacity of pressure-regulated casting is greatly improved compared with gravity casting.

[0050] 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.

[0051] 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.

[0052]

[0053] 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 sudden contraction structure can be expressed as:

[0054]

[0055] Among them, represents the height that the molten metal rises in the small cross-section, represents the filling time; represents the cross-sectional area of the riser tube; represents the cross-sectional area of the cavity. represents the cross-sectional area of the crucible; represents the coefficient of head loss along the way; represents the diameter of the riser tube; represents the density of the molten metal; represents the acceleration due to gravity; represents the initial depth of the riser tube buried in the molten metal in the crucible; represents the depth of the riser tube buried in the molten metal in the crucible when flowing through the small cross-section; represents the surface tension coefficient; represents the contact angle; represents the pressure at the bottom of the small cross-section of the sudden contraction structure.

[0056] When the molten metal flows into the small cross-section instantaneously, the momentum is conserved. Under the action of pressure, the molten metal rises to the position of the sudden contraction structure and will be blocked by the mold shell, and part of the energy is lost (the more energy is lost as the cross-section ratio decreases). The other part of the momentum is released at the small cross-section, and the speed of the molten metal in the small cross-section cavity increases rapidly. At this time, it should be noted that when the pressurization speed is low, the molten metal fills the thin-walled area of the small cross-section due to inertia over a large area, and then cannot obtain subsequent pressure support and begins to fall back, which will make the 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 the casing-type castings and the influence of the variable cross-section dimensions on the forming quality, the variable cross-section ratio is selected here.

[0057] 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.

[0058] In this way, by selecting different cross-section ratios, the influence of relevant dimensions and variable cross-section dimensions on the forming quality can be explored at one time during the test.

[0059] In addition, large thin-walled castings of the casing type have the structure of upper and lower flanges. Therefore, changing the installation sequence of components with variable cross-sections from a sudden contraction structure to a sudden expansion structure more comprehensively conforms to the structure of the actual casting. However, this will cause changes in the filling and feeding conditions of its gating system and will also greatly change its forming quality. At this time, by setting different variable cross-section sizes, the optimal tolerance conditions are explored. Specifically, there are: 1:15, 2:15, 3:15, 4:15, 5:15, 6:15.

[0060] For example, on the horizontal line of the cross-shaped connecting frame 3, test hollow plates 1 with a ratio of 15:1 are respectively set, then test hollow plates 1 with a ratio of 15:2 are set, and then 15:3 and so on are set in sequence. This setting does not follow a fixed arrangement order, and each ratio needs to be set in the upper forming structure;

[0061] In the lower forming structure, for example, on the circumference of the hollow cylinder 2, no less than 8 test hollow plates 1 with different cross-section ratios are selected from the above cross-section ratios for testing.

[0062] As a further illustration of the present invention, based on bottom gating and side gating, thin-walled plate-shaped specimens with different wall thicknesses, variable cross-section plate-shaped specimens with different thicknesses, and spiral specimens with different wall thicknesses are set in the gating system, and flexible combinations of high-throughput preparation arrays of specimens can be achieved.

[0063] As a further illustration of the present invention, with the changes in the pouring sequence, single thin-wall thickness, variable cross-section size, and variable cross-section installation sequence, different effects are brought to the forming quality of the casting. Here, the filling ability, grain size, porosity, dendrite growth mode, segregation, precipitated phase, and properties at different positions of the formed casting can be measured. The number of experiments and the influence of experimental objective factors are reduced, and multi-faceted experimental verification of the forming quality of pressure-regulated casting castings is achieved.

[0064] It should be noted that in this article, relational terms such as first and second 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 term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0065] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention.

Claims

1. A test die for the forming quality of thin-walled superalloy under pressure casting, characterized in that: It includes an upper forming structure, a middle forming structure and a lower forming structure, and the above-mentioned forming structures are all integrally formed; The upper forming structure includes a cross-shaped connecting frame (3) and a plurality of test hollow plates (1), and the plurality of test hollow plates (1) are vertically connected to the top surface of the cross-shaped connecting frame (3); One side of the cross-shaped connecting frame (3) facing away from the upper forming structure is connected with a hollow cylinder (2); One end of the hollow cylinder (2) far away from the cross-shaped connecting frame (3) is connected to the lower forming structure; The lower forming structure also includes a plurality of test hollow plates (1), and the plurality of test hollow plates (1) are horizontally connected to the hollow cylinder (2); A middle forming structure is arranged between the upper forming structure and the lower forming structure; The middle forming structure includes at least two spiral alloy flow structures with different wall thicknesses, and the hollow cylinder (2) penetrates through the two spiral alloy flow structures and is connected; The two spiral alloy flow structures have wall thicknesses of 2 mm and 4 mm respectively, and the thin spiral alloy flow structure is sleeved on the thick spiral alloy flow structure; 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.

2. The test die for the forming quality of high-temperature alloy thin walls by pressure-adjusting casting according to claim 1, characterized in that: The casting form of the upper forming structure includes bottom gating.

3. The test die for the forming quality of high-temperature alloy thin walls in adjusted-pressure casting according to claim 1, characterized in that: The casting form of the lower forming structure includes side gating.

4. The test die for the forming quality of high-temperature alloy thin walls in pressure-regulating casting according to claim 1, wherein: The upper forming structure is used to characterize the influence of bottom gating filling under pressure casting on the forming quality of castings, the middle forming structure is used to characterize the ultimate filling ability with different wall thicknesses under pressure casting, and the lower forming structure is filled step by step from bottom to top to characterize the influence of side gating filling under pressure casting on the forming quality of castings.

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