Nickel-aluminum bronze alloy semi-solid extrusion die and casting method

Abstract

The invention discloses a nickel-aluminum bronze alloy semi-solid extrusion die and a casting method. The casting method comprises the following steps: S1, installing a die, adjusting the opening size of die assembly according to the thickness of the die, and setting basic parameters of a die-casting machine; s2, an electric heating rod is started to preheat the mold, the preheating temperature ranges from 200 DEG C to 300 DEG C, and the interior of the mold is coated with paint; s3, preheating the crucible, brushing the crucible with the prepared coating, after the coating is dried, filling the crucible with the nickel-aluminum bronze original ingot with the foundry returns not exceeding 30%, setting the temperature of the resistance furnace to be 1400 DEG C, after the nickel-aluminum bronze original ingot is fully molten, refining the nickel-aluminum bronze original ingot with the prepared refining agent, and standing for 20 minutes after refining. According to the method, the mold is preheated, so that the casting is good in mold filling and smooth in surface, the nickel-aluminum bronze slurry meeting semi-solid pressure casting is prepared through an electromagnetic stirring method, the structure of the semi-solid slurry is round, fine and uniform in distribution, and the casting quality is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of semi-solid forming, and in particular relates to a nickel-aluminum bronze alloy semi-solid extrusion die and a casting method. Background Art

[0002] Semi-solid technology refers to a material molding technology that processes a solid-liquid mixture containing a non-dendritic solid phase within the solidification temperature range. It has the advantages of low shrinkage, low molding temperature, and fine grains. Semi-solid molding technology is divided into rheoforming and thixoforming technology according to different processing methods. Because rheoforming is to directly mold semi-solid slurry, the production process is short and the cost in industrial applications is much lower. Nickel aluminum bronze is widely used in aerospace, construction, marine and other fields due to its excellent wear resistance, corrosion resistance, high strength, hardness and other excellent properties.

[0003] The mold preheating temperature directly affects the chilling ability of the mold and thus affects the mechanical properties of the alloy and the quality of the die casting. Low mold temperature will make it impossible to release the shrinkage stress generated by the instantaneous solidification of the casting, resulting in cracks on the surface of the casting. In addition, rapid solidification will also prevent shrinkage compensation from being carried out in time, resulting in defects such as shrinkage cavities and shrinkage. It will also cause a large temperature gradient in the casting during the solidification process, accelerate the solidification rate of the casting, make the grain size smaller, and the structure denser. When the mold preheating temperature is too high, the chilling effect is reduced, the grain size becomes coarse, and the mechanical properties of the casting are reduced. At the same time, the adhesion between the casting and the mold is increased, making it difficult to demold the die casting, which is easy to cause mold sticking and tearing, and also shortens the service life of the mold.

[0004] During the semi-solid rheocasting process, the high-temperature semi-solid slurry contacts and flushes with the mold surface under pressure. In addition to mechanical shocks such as wear, high pressure also seriously affects the service life of the mold due to thermal shock. A large number of experimental studies have shown that the main cause of failure of squeeze casting molds is thermal fatigue. Under the action of cyclic thermal stress or cyclic strain, it will eventually lead to cracking. Thermal fatigue starts from the mold surface. Before the cracks form, uneven plastic deformation occurs near the root of the specimen notch, and some wedge-shaped microcracks are formed successively in the area where the plastic strain is most severe. Some of these microcracks will gradually develop into main cracks. In addition, the thermal corrosion between the high-temperature semi-solid alloy melt and the mold cavity surface and the creep behavior of the mold will also reduce its service life. Summary of the invention

[0005] The object of the present invention is to provide a nickel-aluminum bronze alloy semi-solid extrusion die and a casting method to solve the technical problems raised in the background technology.

[0006] To achieve the above object, the specific technical solution of the present invention is as follows: A method for semi-solid extrusion casting of a nickel-aluminum bronze alloy comprises the following steps:

[0007] S1. Install the mold, adjust the size of the mold opening according to the thickness of the mold, and set the basic parameters of the die-casting machine;

[0008] S2. Turn on the electric heating rod to preheat the mold at a temperature of 200-300°C, and apply paint inside the mold;

[0009] S3, preheating the crucible, brushing it with the prepared coating, and after the coating is dried, loading the original nickel-aluminum bronze ingot, with the return charge not exceeding 30%, setting the temperature of the resistance furnace to 1400°C, and refining the original nickel-aluminum bronze ingot with the prepared refining agent after it is fully melted, letting it stand for 20 minutes after refining, skimming, and then performing electromagnetic stirring to prepare a semi-solid slurry, and then introducing the prepared semi-solid slurry into the barrel;

[0010] S4. Squeeze the semi-solid slurry from the barrel into the mold cavity. After pouring, start the press to extrude. After the pressing is completed, maintain the pressure for 20 seconds. After the casting is formed, open the mold and use the thrust of the push rod to eject the nickel-aluminum-bronze alloy casting.

[0011] Preferably, the coating preparation method in step S2 is as follows:

[0012] a. Add water glass to a proper amount of hot water above 50℃ and stir evenly;

[0013] b. Add the soaked lithium bentonite into the water glass aqueous solution and evenly distribute it in the solution;

[0014] c. Add zircon powder and bauxite refractory aggregates into the suspension of lithium-based bentonite, and stir appropriately in the circumferential direction with a glass rod to make the refractory aggregates evenly distributed;

[0015] d. Add starch to the mixed solution and stir evenly, then continue to add a small amount of n-butanol to eliminate bubbles in the coating. After standing for 1 hour, the coating is obtained.

[0016] Preferably, in step S2, the mold is coated with paint by air spraying.

[0017] Preferably, the refining agent in step S3 is C 2 Cl 6 .

[0018] Preferably, the preheating temperature in step S2 is 200-300°C.

[0019] The present invention also relates to a mold used in a semi-solid extrusion casting method of a nickel-aluminum bronze alloy, comprising a movable mold base plate and a fixed mold base plate, a push plate is arranged at the middle part of the surface of the movable mold base plate, a push rod fixing plate is arranged on the surface of the push plate, and a pad is arranged on the surface of the movable mold base plate at the outer side of the push plate, a support plate is arranged on the surface of the pad, a movable mold sleeve plate is arranged on the surface of the support plate, a movable mold is arranged in the movable mold sleeve plate, and the push rod fixing plate is connected to the movable mold through a push rod, a fixed mold sleeve plate is arranged on the surface of the fixed mold base plate, a fixed mold corresponding to the movable mold is arranged in the fixed mold sleeve plate, and electric heating rods are arranged on the support plate, the movable mold, the fixed mold base plate and the fixed mold, and a gate is arranged on the surface of the fixed mold base plate, and the gate passes through the fixed mold and extends to the inner cavity of the movable mold.

[0020] Preferably, a first guide column is disposed on the surface of the push rod fixing plate, and a first guide hole distributed corresponding to the first guide column is disposed on the surface of the support plate.

[0021] Preferably, the surface of the movable mold sleeve is provided with second guide pillars, and the surface of the fixed mold sleeve is provided with second guide holes distributed corresponding to the second guide pillars.

[0022] Preferably, a reset rod is provided on the surface of the push rod fixing plate, and an end of the reset rod passes through the support plate and extends to the inside of the movable mold.

[0023] The semi-solid extrusion die and casting method of the nickel-aluminum bronze alloy of the present invention have the following advantages:

[0024] 1. The present invention preheats the mold to ensure that the casting is well filled and has a smooth surface. The nickel-aluminum-bronze slurry that meets the requirements of semi-solid die casting is prepared by electromagnetic stirring. The structure of the semi-solid slurry is round, fine, and evenly distributed, which greatly improves the quality of the casting.

[0025] 2. The present invention forms a thermal barrier coating by coating the mold, which can not only reduce the heat transfer of high-temperature semi-solid slurry to the mold, reduce the thermal shock of high-temperature semi-solid slurry to the mold, improve the ability of the mold to resist thermal fatigue, and increase the service life of the mold, but also reduce the surface roughness of the casting, improve its surface quality, reduce the tightening force of the casting to facilitate demolding, separate the semi-solid slurry from the mold, avoid fusion welding, and protect the mold cavity from burns. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 It is a structural schematic diagram of the mold in the present invention;

[0028] Explanation of markings in the figure: 1. movable mold base plate; 2. cushion block; 3. push plate; 4. push rod fixing plate; 5. support plate; 6. first guide column; 7. push rod; 8. movable mold sleeve plate; 9. movable mold; 10. fixed mold base plate; 11. fixed mold sleeve plate; 12. fixed mold; 13. gate; 14. second guide column; 15. electric heating rod. DETAILED DESCRIPTION

[0029] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the embodiments of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0030] In the description of the embodiments of the present invention, it should be understood that the terms "length", "vertical", "horizontal", "top", "bottom", etc. indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present invention.

[0031] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0032] In the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0033] The disclosure below provides many different embodiments or examples to implement different structures of the embodiments of the present invention. In order to simplify the disclosure of the embodiments of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the embodiments of the present invention. In addition, the embodiments of the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed.

[0034] In order to better understand the purpose, structure and function of the present invention, the following is a further detailed description of a nickel-aluminum bronze alloy semi-solid extrusion die and a casting method of the present invention in conjunction with the accompanying drawings.

[0035] like Figure 1 As shown, a method for semi-solid extrusion casting of a nickel-aluminum bronze alloy of the present invention comprises the following steps:

[0036] S1. Install the mold, adjust the size of the mold opening according to the thickness of the mold, and set the basic parameters of the die-casting machine;

[0037] S2. Turn on the electric heating rod to preheat the mold, and use air spraying to apply coating to the mold to form a thermal barrier coating, which can not only reduce the heat transfer of the high-temperature semi-solid slurry to the mold, reduce the thermal shock of the high-temperature semi-solid slurry to the mold, improve the ability of the mold to resist thermal fatigue, and increase the service life of the mold, but also reduce the surface roughness of the casting, improve its surface quality, reduce the tightening force of the casting to facilitate demolding, separate the semi-solid slurry from the mold, avoid fusion welding, and protect the mold cavity from being burned;

[0038] S3. Preheat the crucible, apply the prepared coating, wait for the coating to dry, load the original nickel-aluminum bronze ingot, and the recycled material should not exceed 30%. Set the temperature of the resistance furnace to 1400℃. After the original nickel-aluminum bronze ingot is fully melted, use the prepared refining agent C 2 Cl 6 After refining, the mixture was allowed to stand for 20 minutes, and then the slag was removed. Then, electromagnetic stirring was performed to prepare a semi-solid slurry. The stirring current was 450A, the stirring frequency was 6Hz, and the stirring time was 25min. The prepared semi-solid slurry was then introduced into the barrel. 2 Cl 6 It does not absorb moisture and does not need to be dehydrated, so it is very convenient to use and store. It is accepted by general factories. 2 Cl 6 Press into blocks for use;

[0039] S4. Squeeze the semi-solid slurry from the barrel into the mold cavity. After pouring, start the press to extrude. After the pressing is completed, maintain the pressure for 20 seconds. After the casting is formed, open the mold and use the thrust of the push rod to eject the nickel-aluminum-bronze alloy casting.

[0040] The coating preparation method in step S2 is as follows:

[0041] a. Add water glass to a proper amount of hot water above 50℃ and stir evenly;

[0042] b. Add the soaked lithium bentonite into the water glass aqueous solution and evenly distribute it in the solution;

[0043] c. Add zircon powder and bauxite refractory aggregates into the suspension of lithium-based bentonite, and stir appropriately in the circumferential direction with a glass rod to make the refractory aggregates evenly distributed;

[0044] d. Add starch to the mixed solution and stir evenly, then continue to add a small amount of n-butanol to eliminate bubbles in the coating. After standing for 1 hour, the coating is obtained.

[0045] The present invention also relates to a mold used in a semi-solid extrusion casting method of a nickel-aluminum bronze alloy, comprising a movable mold base plate 1 and a fixed mold base plate 10, a push plate 3 is arranged in the middle part of the surface of the movable mold base plate 1, a push rod fixing plate 4 is arranged on the surface of the push plate 3, and a cushion block 2 is arranged on the surface of the movable mold base plate 1 at the outer side of the push plate 3, a support plate 5 is arranged on the surface of the cushion block 2, a movable mold sleeve plate 8 is arranged on the surface of the support plate 5, a movable mold 9 is arranged in the movable mold sleeve plate 8, and the push rod fixing plate 4 is connected to the movable mold 9 through a push rod 7, a fixed mold sleeve plate 11 is arranged on the surface of the fixed mold base plate 10, a fixed mold 12 corresponding to the movable mold 9 is arranged in the fixed mold sleeve plate 11, and an electric heating rod 15 is arranged in the support plate 5, the movable mold 9, the fixed mold base plate 10 and the fixed mold 12, and a gate 13 is arranged on the surface of the fixed mold base plate 10, and the gate 13 penetrates the fixed mold 12 and extends to the inner cavity of the movable mold 9. The surface of the push rod fixing plate 4 is provided with a first guide column 6, the surface of the support plate 5 is provided with a first guide hole corresponding to the first guide column 6, the surface of the movable mold sleeve plate 8 is provided with a second guide column 14, the surface of the fixed mold sleeve plate 11 is provided with a second guide hole corresponding to the second guide column 14, and the surface of the push rod fixing plate 4 is provided with a reset rod, and the end of the reset rod penetrates the support plate 5 and extends to the inside of the movable mold 9. When arranging the position of the push rod 7, in order to avoid damage to the important surface and the reference surface of the semi-solid die casting, a push rod 7 is added to each overflow groove during the design. Since the overflow port is relatively thick, under the action of the thrust of the push rod 7, the semi-solid die casting can be completely taken out of the die casting mold without affecting the surface finish of the casting, thereby improving the quality of the casting. The temperature of the semi-solid metal slurry is between the liquid phase and the solid phase during pouring, which is lower than the temperature of ordinary liquid metal pouring. The mold must be fully preheated before die casting production and kept in a constant temperature range during the die casting process to maintain the fluidity of the die casting alloy during filling, have good formability and improve the surface quality of the casting. Prevent the casting from solidifying prematurely due to low cavity temperature.

[0046] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A method for semi-solid extrusion casting of a nickel-aluminum bronze alloy, characterized in that: The steps include: S1. Install the mold, adjust the size of the mold opening according to the thickness of the mold, and set the basic parameters of the die-casting machine; S2. Turn on the electric heating rod to preheat the mold at a temperature of 200-300°C, and apply paint inside the mold; S3, preheating the crucible, brushing it with the prepared coating, and after the coating is dried, loading the original nickel-aluminum bronze ingot, with the return charge not exceeding 30%, setting the temperature of the resistance furnace to 1400°C, and refining the original nickel-aluminum bronze ingot with the prepared refining agent after it is fully melted, letting it stand for 20 minutes after refining, skimming, and then performing electromagnetic stirring to prepare a semi-solid slurry, and then introducing the prepared semi-solid slurry into the barrel; S4. Squeeze the semi-solid slurry from the barrel into the mold cavity. After pouring, start the press to extrude. After the pressing is completed, maintain the pressure for 20 seconds. After the casting is formed, open the mold and use the thrust of the push rod to eject the nickel-aluminum-bronze alloy casting.

2. The method for semi-solid squeeze casting of a nickel aluminum bronze alloy according to claim 1, characterized in that: The coating preparation method in step S2 is as follows: a. Add water glass to a proper amount of hot water above 50℃ and stir evenly; b. Add the soaked lithium bentonite into the water glass aqueous solution and evenly distribute it in the solution; c. Add zircon powder and bauxite refractory aggregates into the suspension of lithium-based bentonite, and stir appropriately in the circumferential direction with a glass rod to make the refractory aggregates evenly distributed; d. Add starch to the mixed solution and stir evenly, then continue to add a small amount of n-butanol to eliminate bubbles in the coating. After standing for 1 hour, the coating is obtained.

3. The method for semi-solid squeeze casting of a nickel aluminum bronze alloy according to claim 1, characterized in that: In the step S2, the mold is coated with paint by air spraying.

4. The method for semi-solid squeeze casting of a nickel aluminum bronze alloy according to claim 1, characterized in that: The refining agent in step S3 is C2Cl6.

5. The method for semi-solid squeeze casting of nickel aluminum bronze alloy according to claim 1, characterized in that: The preheating temperature in step S2 is 200-300°C.

6. The die used in the semi-solid extrusion casting method of nickel-aluminum bronze alloy according to claims 1-5 is characterized in that: The invention comprises a movable die base plate (1) and a fixed die base plate (10), wherein a push plate (3) is arranged in the middle of the surface of the movable die base plate (1), a push rod fixing plate (4) is arranged on the surface of the push plate (3), a cushion block (2) is arranged on the surface of the movable die base plate (1) at the outer side of the push plate (3), a support plate (5) is arranged on the surface of the cushion block (2), a movable die sleeve plate (8) is arranged on the surface of the support plate (5), a movable die (9) is arranged inside the movable die sleeve plate (8), and the push rod fixing plate (4) is arranged on the outer side of the push plate (3). 4) connected with the movable mold (9) through a push rod (7); a fixed mold sleeve (11) is arranged on the surface of the fixed mold base plate (10); a fixed mold (12) corresponding to the movable mold (9) is arranged in the fixed mold sleeve (11); and electric heating rods (15) are arranged in the support plate (5), the movable mold (9), the fixed mold base plate (10) and the fixed mold (12); a gate (13) is arranged on the surface of the fixed mold base plate (10); and the gate (13) penetrates the fixed mold (12) and extends to the inner cavity of the movable mold (9).

7. The die used in the semi-solid extrusion casting method of nickel-aluminum bronze alloy according to claim 6 is characterized in that: The surface of the push rod fixing plate (4) is provided with a first guide column (6), and the surface of the support plate (5) is provided with a first guide hole distributed corresponding to the first guide column (6).

8. The die used in the semi-solid extrusion casting method of nickel-aluminum bronze alloy according to claim 6 is characterized in that: The surface of the movable mold sleeve (8) is provided with second guide pillars (14), and the surface of the fixed mold sleeve (11) is provided with second guide holes distributed corresponding to the second guide pillars (14).

9. The die used in the semi-solid extrusion casting method of nickel-aluminum bronze alloy according to claim 6 is characterized in that: A reset rod is provided on the surface of the push rod fixing plate (4), and the end of the reset rod passes through the support plate (5) and extends to the inside of the movable mold (9).

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