Runner system for melt depth uniform supercooling nucleation and application method thereof

Abstract

The invention belongs to the field of material processing, and particularly relates to a pouring gate system for melt depth uniform supercooling nucleation and an application method of the pouring gate system. The pouring gate system for melt depth uniform supercooling nucleation comprises a pouring gate and at least one main pouring gate connected with the pouring gate, the main pouring gate is an S-shaped bent and extended pipeline, and the cross section of the pipeline is gradually reduced from an inlet to an outlet; an outlet of the main pouring gate is connected with the casting mold. Alloy melt is poured from the pouring gate and flows into the continuous S-shaped main pouring gate, the impact temperature of the melt in the center of the pouring gate pipe is far lower than that of the pipe wall surface of the melt under the inertia effect every time when the main pouring gate turns, so that the melt is in a supercooled state to excite nucleation inside the melt, and through continuous and repeated longitudinal and transverse stirring, the melt is cooled to form a core. In this way, melt entering the casting mold through the S-shaped main pouring gate is in the same supercooled state, meanwhile, dendritic crystal falling is increased through turbulent flow in the melt, and nucleation proliferation is the superposition of the strong supercooled proliferation effect and the convective stirring proliferation effect.

Description

Technical Field

[0001] This invention belongs to the field of materials processing, and in particular relates to a gating system for uniform subcooling nucleation of melt and its application method. Background Technology

[0002] In casting production, it is generally desirable to obtain a fine-grained structure, as grain refinement can significantly improve the mechanical properties of materials. Therefore, exploring and optimizing technical routes to refine the grains during the solidification process of castings is an important direction for continuous research in the field of materials.

[0003] Currently, grain refinement methods mainly include two categories: adding modifiers and applying external fields. Among them, adding modifiers can generally only improve the grain size by 1-2 grades under given solidification conditions, and the refinement effect is limited. On the other hand, applying external fields is not suitable for the solidification process of many castings. The role of applying external fields is generally to increase the convection of the melt and break up dendrites, thereby increasing the nucleation rate and refining the dendrites.

[0004] Increasing melt undercooling is an efficient way to improve the nucleation rate, but since the solidification process is an inside-out process, deep undercooling of the melt is generally difficult to achieve. If deep undercooling and convection of the melt can be achieved, it will be very beneficial to grain nucleation and proliferation during the solidification process, resulting in a fine-grained casting structure. This invention focuses on achieving deep undercooling of the melt through the gating system body during the forming process without the aid of external fields or high pressure equipment, thereby enhancing the nucleation rate during the solidification process and achieving a fine-grained casting structure. Summary of the Invention

[0005] The purpose of this invention is to provide a gating system for uniform subcooling and nucleation of melt in depth. Through the structural design of a continuous S-shaped gating system, the system achieves synchronous subcooling in depth and internal scouring of the melt under the dual action of the melt's own gravity and inertia, thereby promoting uniform nucleation and grain proliferation inside the melt, and ultimately achieving the technical effect of refining the grains of the casting.

[0006] In existing gating systems, as the melt flows forward longitudinally, a solidified layer rapidly forms on the gating wall. The core of the melt is a high-temperature region, and the liquid-solid phase interval between the solidified layer and the high-temperature core region is very narrow. This is a supercooling of the melt wall region. Although the melt is in a turbulent state, the core of the melt is a non-supercooled region, resulting in a small number of nucleated grains. Furthermore, the grains are prone to remelting after nucleation. The dendrite shedding and grain proliferation effects caused by melt scouring are not significant.

[0007] During the flow of the melt, if the lateral movement of the melt is strengthened, the core melt can be in continuous contact with the cold wall surface of the gating. This repeated lateral movement makes the core of the melt and the edge area of ​​the tube wall reach a highly similar supercooled state, thereby increasing the nucleation rate. At the same time, the strong scouring effect of the melt can further promote the dendrite detachment of nucleated grains, making the grain proliferation effect more obvious.

[0008] The objective of this invention can be achieved through the following technical solutions: A gating system for uniform subcooling nucleation of melt depth includes a gate and at least one main gating connected to the gate. The main gating is an S-shaped, bend-extending pipe with a cross-section that gradually decreases from the inlet to the outlet. The outlet of the main gating is connected to the mold.

[0009] Molten alloy is poured into the gate and flows into a continuous S-shaped main runner. At each bend, the melt in the center of the runner, due to inertia, experiences an impact temperature much lower than the runner wall, thus creating a supercooled state that stimulates nucleation within the melt. Through this continuous and repeated longitudinal and transverse stirring, the melt entering the mold through the S-shaped main runner is in a uniform supercooled state, i.e., homogeneous supercooling. This uniform supercooling effectively inhibits the growth of columnar crystals during solidification, resulting in smaller overall grain size variations in the casting. Simultaneously, the turbulence within the melt increases dendrite shedding. This nucleation and proliferation effect is a superposition of strong supercooling and convective stirring. This intense nucleation and proliferation is significantly superior to the effects of ordinary convective stirring or supercooling.

[0010] Preferably, the main gating system is divided into 2-3 sections, each with an equal diameter, and the diameter gradually decreases from the inlet section to the outlet section. Specifically, the diameter of the first inlet section (DL1) is larger than that of the second middle section (DL2), which is larger than that of the third outlet section (DL3). This design ensures that the molten material in the main gating system is void-free and in close contact with the cold wall surface. Gas in the molten material can be discharged during the flow process, which also facilitates slag removal and improves the quality of the casting.

[0011] Preferably, the main runner is arranged at a downward slope from the inlet to the outlet. Since the S-shaped pipe increases fluid resistance, under non-pressure casting conditions, if the S-shaped pipe is arranged at a downward slope, gravity will provide the flow propulsion.

[0012] Preferably, the main gating system has a circular cross-section. This design results in uniform stress distribution, low resistance, ease of machining, and good connection.

[0013] Preferably, the S-shaped extension of the main runner has a bend that changes from gentle to rapid. The advantage of this design is that when the melt enters the main runner from the gate, the initial flow state is unstable. By setting a gentle inlet bend, defects such as splashing, air entrapment, and oxide inclusions caused by violent impact can be effectively avoided. Simultaneously, it reduces erosion and wear on the inner wall of the runner, extending the mold's service life. As the bend gradually increases, the degree of curvature intensifies, steadily increasing the inertial impact strength of the melt at the bend. This gradient stirring effect allows the central melt to repeatedly and uniformly impact the low-temperature tube wall, continuously stimulating supercooled nucleation and avoiding localized overcooling caused by a single violent bend. This maintains a high degree of uniform supercooling of the melt, providing sufficient and evenly distributed nucleus sources for grain refinement. At this stage, the strong supercooling effect and the convection shear effect are superimposed, stimulating a large number of new nuclei and promoting dendrite breakage and shearing to form secondary nuclei, significantly improving the nucleation and multiplication effect and providing a high-density, fine-grained nucleus reserve for the mold.

[0014] The application method of the above-mentioned gating system for uniform melt depth undercooling nucleation includes the following steps: S1, Melt the alloy metal at a melting temperature of 720℃ and set aside the molten alloy liquid; S2, pour the molten alloy liquid from step S1 into the gate, and the alloy liquid flows from the gate into the S-shaped main gating pipe, and finally flows into the mold to solidify and form the shape.

[0015] Preferably, the alloy metal in S1 is a tin bronze alloy, wherein the mass ratio of tin in the tin bronze alloy is 10 wt%, the mass ratio of iron is 0.05 wt%, the mass ratio of phosphorus is 0.03 wt%, and the balance is copper.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention is that the melt in the center of the main gating tube changes direction due to the S-shaped bend, and actively impacts the cold wall from the center of the flow channel. At the same time, the strong supercooling nucleation and proliferation of the cold wall due to the inertial impact and the dendrite shedding and convection proliferation of the longitudinal and transverse stirring are achieved. The two are coupled and superimposed in the same space and the same process, and the nucleation and proliferation effect is very significant, so the grains are also finer and the material properties are greatly improved.

[0017] 2. The S-shaped main gating pipe in this invention has a short longitudinal straight length and occupies a small area, so this pipe design makes it easier to cast multiple molds at once and achieve the same quality for each product.

[0018] 3. This invention can effectively improve and adjust the grain size of castings, and realize the preparation of fine-grained castings. Its grain refinement is stronger than that of general alternating magnetic field or mechanical stirring, and also stronger than that of general ultrasonic vibration. The process is simple to implement, the overall production cost is low, and it has a wide range of application value.

[0019] 4. The S-shaped extension pipe design of the main gating system can achieve gradient control of stable inlet flow and strong gradient nucleation in the middle and end sections. In conjunction with the tapered pipe diameter structure, it maximizes nucleation efficiency while ensuring smooth filling, and finally obtains castings with fine grains, uniform structure, no pores and excellent mechanical properties. Attached Figure Description

[0020] Figure 1 This is a top view of the structural schematic diagram of the gating system of the present invention.

[0021] Figure 2 This is a partially enlarged view of the gating system of the present invention.

[0022] Figure 3 This is a front view of the structural schematic diagram of the gating system of the present invention.

[0023] Figure 4 This is a top view of the structural schematic diagram in Comparative Example 1.

[0024] Wherein, 1-gate, 2-main runner. Detailed Implementation

[0025] The present invention will be further described below with reference to the embodiments: Example 1

[0026] A gating system for uniformly subcooled nucleation of melt, such as Figure 1 , 2 As shown, the system includes a gate 1 and eight main runners 2 connected to the gate 1. Each main runner 2 is an S-shaped, curved pipe with a circular cross-section whose diameter gradually decreases from the inlet to the outlet. The outlet of the main runner 2 is connected to the mold. The main runner 2 is divided into three sections, each with an equal diameter, and the diameter gradually decreases from the inlet to the outlet. The curvature of the S-shaped main runner 2 changes from gentle to rapid. The inlet and outlet of the main runner 2 are horizontally aligned. Specifically, the diameter of the first inlet section DL1 of the main runner 2 is 15 mm, the second section DL2 is 13.5 mm, and the third section DL3 is 12 mm. The total length of the main runner 2 is 60 cm.

[0027] A tin bronze alloy with an alloy composition of 10 wt% tin, 0.05 wt% iron, 0.03 wt% phosphorus, and the balance being copper was melted and pre-prepared at 720℃ for later use. 2 kg of molten tin bronze alloy was poured into gate 1, passed through the S-shaped gating system, and then entered the mold for solidification.

[0028] Example 2

[0029] A gating system for uniformly subcooled nucleation of melt, such as Figure 1-3As shown, the system includes a gate 1 and eight main runners 2 connected to the gate 1. Each main runner 2 is an S-shaped, curved pipe with a circular cross-section whose diameter gradually decreases from the inlet to the outlet. The outlet of the main runner 2 is connected to the mold. The main runner 2 is divided into three sections, each with an equal diameter, and the diameter gradually decreases from the inlet to the outlet. The curvature of the S-shaped main runner 2 changes from gentle to rapid. The main runner 2 slopes downwards at a 45° angle from the inlet to the outlet. Specifically, the diameter of the first inlet section DL1 of the main runner 2 is 15 mm, the second section DL2 is 13.5 mm, and the third section DL3 is 12 mm. The total length of the main runner 2 is 90 cm.

[0030] A tin bronze alloy with an alloy composition of 10 wt% tin, 0.05 wt% iron, 0.03 wt% phosphorus, and the balance being copper was melted and pre-prepared at 720℃ for later use. 2 kg of molten tin bronze alloy was poured into gate 1, passed through the S-shaped gating system, and then entered the mold for solidification.

[0031] Example 3

[0032] A gating system for uniformly subcooled nucleation of melt, such as Figure 1-3 As shown, the system includes a gate 1 and eight main runners 2 connected to the gate 1. Each main runner 2 is an S-shaped, curved pipe with a circular cross-section whose diameter gradually decreases from the inlet to the outlet. The outlet of the main runner 2 is connected to the mold. The main runner 2 is divided into three sections, each with an equal diameter, and the diameter gradually decreases from the inlet to the outlet. The curvature of the S-shaped main runner 2 changes from gentle to rapid. The inlet to outlet of the main runner 2 is flat, as in the embodiment. Specifically, the diameter of the first inlet section DL1 of the main runner 2 is 15 mm, the diameter of the second section DL2 is 13.5 mm, and the diameter of the third section DL3 is 12 mm. The total length of the main runner 2 is 90 cm.

[0033] A tin bronze alloy with an alloy composition of 10 wt% tin, 0.05 wt% iron, 0.03 wt% phosphorus, and the balance being copper was melted and pre-prepared at 720℃ for later use. 2 kg of molten tin bronze alloy was poured into gate 1, passed through the S-shaped gating system, and then entered the mold for solidification.

[0034] Example 4

[0035] A gating system for uniformly subcooled nucleation of melt, such as Figure 1-3As shown, the system includes a gate 1 and eight main runners 2 connected to the gate 1. Each main runner 2 is an S-shaped, curved pipe with a circular cross-section whose diameter gradually decreases from the inlet to the outlet. The outlet of the main runner 2 is connected to the mold. The main runner 2 is divided into three sections, each with an equal diameter, and the diameter gradually decreases from the inlet to the outlet. The curvature of the S-shaped main runner 2 changes from gentle to rapid. The main runner 2 slopes downwards at a 70° angle from the inlet to the outlet. Specifically, the diameter of the first inlet section DL1 of the main runner 2 is 15 mm, the second section DL2 is 13.5 mm, and the third section DL3 is 12 mm. The total length of the main runner 2 is 100 cm.

[0036] A tin bronze alloy with an alloy composition of 10 wt% tin, 0.05 wt% iron, 0.03 wt% phosphorus, and the balance being copper was melted and pre-prepared at 720℃ for later use. 2 kg of molten tin bronze alloy was poured into gate 1, passed through the S-shaped gating system, and then entered the mold for solidification.

[0037] Comparative Example 1 The gating system in this comparative example is similar to that in Example 1, except that the shape of the main gating is not S-shaped, but straight. See details below. Figure 4 As shown.

[0038] A tin bronze alloy with an alloy composition of 10 wt% tin, 0.05 wt% iron, 0.03 wt% phosphorus, and the balance being copper was melted and pre-prepared at 720℃ for later use. 2 kg of molten tin bronze alloy was poured into the gating system and entered into 8 horizontal runners, each 60 mm long, before entering the mold for solidification.

[0039] Comparative Example 2 The gating system in this comparative example is similar to that in Example 2, except that the shape of the main gating is not S-shaped, but straight.

[0040] A tin bronze alloy with an alloy composition of 10 wt% tin, 0.05 wt% iron, 0.03 wt% phosphorus, and the balance copper was melted and pre-cast at 720℃ for later use. Two kilograms of molten tin bronze alloy were poured into a gating system and fed into eight [unclear - possibly a specific process or process]. Figure 4 The straight and horizontal runners are 90mm long and enter the mold to solidify.

[0041] Comparative Example 3 The gating system in this comparative example is similar to that in Example 2, except that the shape of the main gating is not S-shaped, but straight.

[0042] A tin bronze alloy with an alloy composition of 10 wt% tin, 0.05 wt% iron, 0.03 wt% phosphorus, and the balance copper was melted and pre-cast at 720℃ for later use. Two kilograms of molten tin bronze alloy were poured into a gating system and fed into eight [unclear - possibly a specific process or process]. Figure 4 The straight and horizontal runners are 100mm long and enter the mold to solidify.

[0043] Test results: The casting products prepared in the examples and comparative examples were tested, and the specific test results are shown in the table below: Comparison of Grain Size and Microstructure Observation Test Results Example / Test Item Example 1 Comparative Example 1 Example 2 Example 3 Example 4 Comparative Example 2 Comparative Example 3 Grain size 8-20 micrometers 20-100 micrometers 4-10 micrometers Failed to form in the mold 3-7 micrometers 20-100 micrometers Failed to form in the mold Organization and Segregation The second phase is uniformly distributed, and the structure is dense and columnar-free. There is obvious segregation, columnar crystal structure, and micropores. The second phase is uniformly distributed, and the structure is dense and columnar-free. Failed to form in the mold The second phase is uniformly distributed, and the structure is dense and columnar-free. There is obvious segregation, columnar crystal structure, and micropores. Failed to form in the mold As shown in Table 1 above, the cast products obtained in Examples 1, 2, and 4 have finer grain sizes, improving the grain size grade by more than three levels compared to ordinary metal mold casting. Due to the finer grains, the phenomenon of second-phase segregation is also significantly reduced, and the second phase is evenly distributed. This indicates that the present invention can significantly improve the proliferation of crystal nuclei during solidification, thereby significantly refining the microstructure grains. The finer grain size in Example 2 indicates that increasing the inclination of the main runner can give the melt better fluidity under gravity, allowing it to flow a longer distance in the S-shaped tube. Melt supercooling and grain proliferation are more pronounced, resulting in finer grains and significantly improved material properties. In Example 3, due to the resistance within the S-shaped tube consuming some kinetic energy, the tube is too long and there is no fluidity at the tail end of the runner. Examples 2 and 4 show that by increasing the inclination angle, the flow velocity can be increased by gravity, thereby increasing the melt's flow capacity in the S-shaped tube and obtaining better supercooling.

[0044] The above description of the embodiments is intended to enable those skilled in the art to understand and use the present invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments. Improvements and modifications made by those skilled in the art based on the principles of the present invention, without departing from the scope of the invention, should be within the protection scope of the present invention.

Claims

1. A gating system for uniformly subcooled nucleation of melt, comprising a gating gate (1) and at least one main gating system (2) connected to the gating gate (1), characterized in that: The main gating system (2) is an S-shaped bend extending pipe, the cross-section of which gradually decreases from the inlet to the outlet; the outlet of the main gating system (2) is connected to the mold.

2. The gating system according to claim 1, characterized in that: The main gating system (2) is divided into 2-3 sections, each with the same diameter.

3. The gating system according to claim 1, characterized in that: The main gating system (2) is arranged at a downward slope from the inlet to the outlet.

4. The gating system according to claim 1, characterized in that: The main gating system (2) has a circular cross-section.

5. The gating system according to claim 1, characterized in that: The S-shaped extension of the main gating system (2) has a bend that varies from gentle to rapid.

6. The application method of the gating system for uniformly subcooled nucleation of melt depth as described in claim 1, comprising the following steps: S1, Melt the alloy metal and set aside the molten alloy liquid; S2, pour the molten alloy liquid from step S1 into the gate (1), and the alloy liquid flows from the gate (1) into the S-shaped main gating (2) pipe, and finally flows into the mold to solidify and form.

7. A method for applying the gating system as described in claim 1, characterized in that... The alloy metal in S1 is a tin bronze alloy, in which the mass ratio of tin is 10 wt%, iron is 0.05 wt%, phosphorus is 0.03 wt%, and the balance is copper.

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