Pouring device for railway frog casting

Abstract

The utility model discloses a pouring device for a railway frog casting, which comprises an upper sand mold and a lower sand mold, and the upper sand mold and the lower sand mold are used for enclosing to form a sand mold cavity for pouring and molding the railway frog casting. A pouring gate device and an air inflation device are arranged at the two opposite ends of the pouring device correspondingly, the pouring gate device is used for pouring molten metal into the sand mold cavity, and the air inflation device is used for filling protective gas into the sand mold cavity so as to discharge air in the sand mold cavity to the outside. The pouring device of the railway frog casting is provided with the air charging device, the air charging device is connected with the protective gas, the protective gas is charged into the sand mold through the air charging device before the casting mold is poured so as to discharge the air in the cavity of the sand mold, and the pouring is carried out under the condition that the cavity of the sand mold is filled with the protective gas. Molten metal is subjected to mold filling under protection of protective gas, molten steel is prevented from absorbing air, and therefore the air hole defect of a casting is avoided.

Description

Technical Field

[0001] This utility model relates to the technical field of high manganese steel frog castings, and in particular, to a casting device for railway frog castings. Background Technology

[0002] High-manganese steel railway frogs are an important component of railway lines, generally manufactured using casting. High-manganese steel railway frogs are mostly shell-shaped with a large length-to-diameter ratio, resulting in a relatively complex structure. Their length is generally around 6 meters, and the main wall thickness is approximately 25 mm. The casting method for high-manganese steel railway frogs involves hardening the upper and lower sand molds separately, demolding them, and then assembling the casting. A cavity corresponding to the shape of the casting is formed between the upper and lower sand molds. High-temperature molten metal is poured into this cavity, and after cooling and solidification, the cast product is obtained. During the process of the molten metal filling the cavity between the upper and lower sand molds, a vigorous chemical reaction occurs between the surface of the high-temperature molten metal and the air in the sand mold cavity. The interaction between the molten metal and substances such as oxygen, nitrogen, and water in the air leads to an increase in the content of gaseous elements such as oxygen, nitrogen, and hydrogen in the molten metal, resulting in decreased performance, increased defects, and in severe cases, rendering the casting unusable.

[0003] The casting devices commonly used in railway frogs, such as Figure 1 As shown, during casting, the gating end of the sand mold is typically raised to tilt the mold at a certain angle, increasing the flow rate of molten steel to facilitate rapid filling of the mold cavity. Molten steel is introduced from one end of the gating and flows a considerable distance to reach the other. Due to the complex internal structure of the sand mold cavity, the molten steel flow is turbulent after entering the cavity, and the chemical reaction between the molten steel surface and the air inside the cavity is intense. This leads to severe air absorption problems in the molten steel further from the gating point and with a longer flow path (especially the surface layer), resulting in porosity defects in the casting after solidification and reducing product quality.

[0004] To address the aforementioned problems, technicians have adopted a method of adding a slag collection bag to the end of the casting furthest from the gate. For example, Chinese patent CN112024821B discloses a forklift mold, a forklift casting method, and a forklift casting. This method collects the molten metal that initially flows the furthest distance into the sand mold, preventing it from becoming part of the casting. After solidification, the molten steel is removed as a riser, which improves casting quality to some extent. However, because the interface between the slag collection bag and the casting is at the bottom, and a large flow rate and velocity are required during molten steel filling, the connection between the slag collection bag and the casting fills very quickly in the initial stage of filling. This causes the surface layer of molten steel with severe air absorption to be lifted by the subsequent inflow of molten steel, becoming part of the casting near the top surface at the far end of the gate. In actual production, the areas with severe porosity in high-manganese steel railway forks are precisely in the region near the top surface of the casting far from the gate. Utility Model Content

[0005] This utility model provides a casting device for railway frog castings to solve the technical problem of porosity defects on the castings caused by the contact between molten metal and air during the casting of high manganese steel frogs.

[0006] According to one aspect of the present invention, a casting device for railway frog castings is provided, comprising an upper sand mold and a lower sand mold, wherein the upper sand mold and the lower sand mold are used to enclose and form a sand mold cavity for casting railway frog castings, wherein a gating device and an air filling device are respectively provided at opposite ends of the casting device, the gating device being used to pour molten metal into the sand mold cavity, and the air filling device being used to fill the sand mold cavity with protective gas to expel the air in the sand mold cavity to the outside.

[0007] Furthermore, the inflation device includes an air inlet pipe and a bleed air hose. The air inlet pipe extends downward from the upper sand mold into the sand mold cavity. The bleed air hose is detachably connected to the air inlet pipe and is used to connect to a protective gas device.

[0008] Furthermore, the end of the air duct is provided with an air duct end cap, which is used for detachable connection with the air inlet pipe.

[0009] Furthermore, the bleed end cap includes a bleed end, a connecting end, and a connecting cover. The bleed end is used to connect to a protective gas device, the connecting end is used to extend into the air inlet pipe, and the connecting cover is disposed between the bleed end and the connecting end. The connecting cover is used to connect the bleed hose to the air inlet pipe.

[0010] Furthermore, the upper sand mold has a countersunk hole surrounding the air inlet pipe, which is used to accommodate the connecting cover on the air intake end cover.

[0011] Furthermore, the inflation device also includes a sealing cover, which is used to be installed on the air inlet pipe after the upper and lower sand molds are assembled to prevent air outside the sand mold cavity from forming convection with the gating device through the air inlet pipe and absorbing moisture.

[0012] Furthermore, the inflation device also includes a sealing element, which is inserted into the air inlet pipe during molten metal pouring to prevent molten steel from flowing out of the air inlet pipe.

[0013] Furthermore, a sealing strip is provided on the contact surface between the upper and lower sand molds. The sealing strip is arranged along the circumference of the sand mold cavity to improve the sealing performance after the upper and lower sand molds are assembled.

[0014] Furthermore, a slag collection bag is provided at the end of the sand mold cavity away from the gating device.

[0015] Furthermore, the air-filling device is positioned above the slag collection bag and is connected to the slag collection bag.

[0016] This utility model has the following beneficial effects:

[0017] This utility model discloses a casting device for railway frog castings. An upper sand mold and a lower sand mold are used to enclose the sand mold cavity for casting the railway frog. A gating device and a gas filling device are respectively installed at opposite ends of the casting device. Protective gas is then introduced into the sand mold cavity before casting, allowing air in the sand mold cavity to be expelled to the outside. The railway frog casting is then cast under the condition that the sand mold cavity is filled with protective gas. This ensures that the molten metal fills the mold under the protection of the protective gas, thus preventing the molten metal from absorbing air during solidification. This avoids porosity defects in the railway frog casting and improves the quality of the railway frog casting.

[0018] In addition to the objectives, features, and advantages described above, this utility model has other objectives, features, and advantages. The present utility model will now be described in further detail. Attached Figure Description

[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an undue limitation of the present invention. In the drawings:

[0020] Figure 1 A schematic diagram of an existing casting apparatus for railway frog castings;

[0021] Figure 2 This is a schematic diagram of the casting device for railway frog castings according to the present invention;

[0022] Figure 3 This is a schematic diagram of the internal structure of the present invention;

[0023] Figure 4 This is a schematic diagram of the structure of the sealing strip of this utility model;

[0024] Figure 5 This is a schematic diagram of the air intake end cap.

[0025] Figure 6 This is a schematic diagram of the slag collection bag of this utility model;

[0026] Figure 7 This is a schematic diagram of the sealing cap of this utility model.

[0027] In the diagram: 1. Lower sand mold; 2. Upper sand mold; 3. Gating device; 4. Vent hole; 5. Air priming hose; 6. Slag collection bag; 7. Sand mold cavity; 8. End cap; 81. Air priming end; 82. Connecting end; 83. Connecting cover; 9. Air inlet pipe; 10. Sealing component; 11. Sealing cover; 12. Sealing strip; 13. Countersunk hole. Detailed Implementation

[0028] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0029] See Figures 2 to 7 An embodiment of the first aspect of this utility model provides a casting device for railway frog castings, including an upper sand mold 2 and a lower sand mold 1. The upper sand mold 2 and the lower sand mold 1 are used to enclose and form a sand mold cavity 7 for casting railway frog castings. The casting device for railway frog castings is provided with a gating device and an air filling device at opposite ends. The gating device 3 is used to pour molten metal into the sand mold cavity, and the air filling device is used to fill the sand mold cavity 7 with protective gas to discharge the air in the sand mold cavity 7 to the outside.

[0030] This utility model discloses a casting device for railway frog castings. An upper sand mold 2 and a lower sand mold 1 enclose a sand mold cavity 7 for casting the railway frog. A gating device 3 and an air-filling device are respectively installed at opposite ends of the casting device. Protective gas is then introduced into the sand mold cavity 7 before casting, allowing air in the cavity to be expelled to the outside. The railway frog casting is then cast while the sand mold cavity 7 is filled with protective gas. This ensures that the molten metal fills the mold under the protection of the protective gas, preventing the molten metal from absorbing air during solidification. This avoids porosity defects in the railway frog casting and improves its quality.

[0031] Optionally, the molten metal is molten steel.

[0032] In this embodiment, the gating device 3 extends downward from the upper sand mold 2 to the sand mold cavity 7. To facilitate the pouring of molten metal, the gating device 3 can be designed as a funnel-shaped structure that is wider at the top and narrower at the bottom, or it can be any other structure that facilitates pouring. The pouring device is also provided with a vent 4, the outlet of which is located on the upper sand mold 2. The vent 4 is used to discharge the gas in the sand mold cavity 7. The vent 4 is connected to the sand mold cavity 7 and is used to discharge the air in the sand mold cavity 7 when protective gas is filled into the sand mold cavity. It can also be used to discharge the gas in the sand mold cavity 7 during casting pouring. During casting pouring, the gating end of the sand mold is generally raised to tilt the sand mold at a certain angle to increase the flow rate of the molten metal to facilitate rapid filling of the sand mold cavity. Therefore, the gating end of the pouring device can be called the upper end, and the other end of the pouring device away from the gating end can be called the lower end.

[0033] In this embodiment, the upper sand mold 2, at the end furthest from the gating device 3, has a through hole communicating with the sand mold cavity 7. The gas filling device is disposed on the through hole, which should be located as far as possible at the end of the sand mold cavity so that when the protective gas is filled, the protective gas can completely expel all the air in the sand mold cavity 7 from the gating device 3 or the vent hole 4 to the outside through the lower end of the gating device. The protective gas can be argon or helium, or other gases with very stable chemical properties that do not easily react with molten steel. This application uses a gas filling device to fill the sand mold cavity 7 with a protective gas such as argon or helium, and performs molten metal pouring under the condition that the sand mold cavity 7 is filled with protective gas, which can prevent the molten steel from absorbing air and causing porosity defects.

[0034] In this embodiment, see Figure 5 The inflation device includes an air inlet pipe 9 and a priming hose 5. The air inlet pipe 9 extends downward from the upper sand mold 2 into the sand mold cavity 4. The priming hose 5 is detachably connected to the air inlet pipe 9 and is used to connect to a protective gas device. The air inlet pipe 9 is located on the upper sand mold 2 and needs to be connected to the protective gas device via the priming hose 5 to inflate the protective gas into the sand mold cavity 7. Further, the air inlet pipe 9 used in this application can be made of metal material, preferably steel pipe. The diameter of the through hole matches the outer diameter of the steel pipe, which serves to fix and limit the steel pipe, preventing it from falling off or shaking when the protective gas is inflated. After the casting of the railway frog casting is completed, the steel pipe can be removed and reused. The detachable connection between the air inlet pipe 9 and the priming hose 5 facilitates the disassembly of the priming hose 5 and the connection of a sealing cap 11 to the air inlet pipe 9 after inflation. Specifically, the air inlet pipe 9 and the priming hose 5 can be connected by threaded connection, snap-fit, or other methods for easy assembly and disassembly. Since the intake pipe 9 is made of steel, when using threaded connection, the bleed hose 5 can be equipped with a threaded connector. If a snap-fit ​​connection is used, the connector 82 on the bleed hose 5 can be made of a material with a certain degree of elasticity, so that the connection between the bleed hose 5 and the intake pipe 9 is more secure.

[0035] In this embodiment, an air duct end cap 8 is provided at the end of the air duct 5, which is used for detachable connection with the air inlet pipe 9. The air duct end cap 8 includes an air duct end 81, a connecting end 82, and a connecting cap 83. The connecting end 82 is used to extend into the air inlet pipe 9; the air duct end 81 is used to connect to the protective gas device; and the connecting cap 83 is disposed between the air duct end 81 and the connecting end 82, and is used to fix the air duct 5 to the air inlet pipe. The connecting end 82 is made of an elastic material, such as rubber, and has several protrusions and recesses, which are spaced apart. The protrusions are used to lock the connecting end 82 against the pipe wall when it is inserted into the air inlet pipe 9, thus sealing it and preventing the protective gas from leaking out from the gap between the air inlet pipe 9 and the air duct end cap 8. At the same time, it allows the air in the sand mold cavity 7 to be discharged from the exhaust port 4 at the other end. The bleed end 81 is used to connect to the output end of the protective gas device. The bleed end 81 and the connecting end 82 have interconnected through holes for the passage of protective gas. The connecting cover 83 is provided with a threaded structure or a snap-fit ​​structure that mates with the air inlet pipe 9, for secure connection with the air inlet pipe and to prevent the bleed hose from falling off during inflation. By providing a bleed end cover 8 at the end of the bleed hose 5, inflation operation is facilitated, protective gas leakage and waste are prevented, and inflation pressure is maintained to ensure complete expulsion of air from the sand mold cavity.

[0036] In this embodiment, the upper sand mold 2 has a countersunk hole 13 surrounding the air inlet pipe 9. The countersunk hole 13 is used to accommodate the connecting cap 83 on the air intake end cap 8. The depth of the countersunk hole 13 should not be less than the height of the connecting cap 83, so that the countersunk hole 13 can completely accommodate the connecting cap 83, and the height of the connecting cap 83 placed in the countersunk hole should not be higher than the upper surface of the upper sand mold 2, so that sand can enter the countersunk hole 13 during the inflation operation and prevent sand from falling into the sand mold cavity 7.

[0037] In this embodiment, see Figure 7 The inflation device also includes a sealing cover 11, which is installed on the air inlet pipe 9 after the upper sand mold 2 and the lower sand mold 1 are assembled to prevent air outside the mold cavity from forming convection with the vent riser at the gating end through the air inlet pipe 9 and absorbing moisture. The sealing cover 11 can be a rubber cover. During the waiting period after the upper sand mold 2 and the lower sand mold 1 are assembled and before casting (this process is generally 10 to 30 hours), it prevents air outside the sand mold cavity from forming convection with the vent riser (including the channel of the gating device 3 and the vent hole 4) at the upper end of the casting device through the air inlet pipe 9 at the lower end of the casting device, thus preventing moisture absorption on the surface of the sand mold cavity 7.

[0038] In this embodiment, the inflation device further includes a sealing element 10, which is inserted into the air inlet pipe 9 during molten metal pouring to prevent molten steel from flowing out of the air inlet pipe 9. The sealing element 10 can be a round steel bar with a diameter slightly smaller than that of the air inlet pipe 9. The gap between the round steel bar and the inner hole of the air inlet pipe 9 is small, which can prevent the protective gas in the sand mold cavity 7 from overflowing when the molten steel is filled into the sand mold cavity 7. The main function of inserting the round steel bar is to prevent molten steel from flowing out of the air inlet pipe 9 during molten metal pouring, thus preventing a "blasting" accident.

[0039] In this embodiment, see Figure 7 A sealing strip 12 is provided on the contact surface between the upper sand mold 2 and the lower sand mold 1. The sealing strip 12 is arranged circumferentially along the sand mold cavity 7 to improve the sealing performance after the upper and lower sand molds are closed. The sealing strip 12 can be set on the upper sand mold 2 or the lower sand mold 1. The sealing strip 12 is located on the outside of the sand mold cavity 7, which improves the sealing performance after the upper sand mold 2 and the lower sand mold 1 are closed. The sealing strip 12 is a sealing mud strip, which makes the sand mold cavity 7 a relatively closed and independent space, which is conducive to the complete removal of air in the sand mold cavity 7; at the same time, it can prevent air from outside the sand mold from entering the sand mold cavity 7 through the gap between the upper and lower sand molds 1 during the process of filling the sand mold cavity 7 with molten steel (after argon gas has been stopped filling the sand mold before this).

[0040] In this embodiment, a slag collection bag 6 connected to the sand mold cavity 7 is provided at the end furthest from the gating device 3. Before pouring the molten metal, the upper sand mold 2 and the lower sand mold 1 are closed and waiting for pouring, a process that generally takes 10 to 30 hours. During this period, the inner surface of the sand mold cavity 7 will gradually absorb moisture, and there may also be some impurities such as sand inside the sand mold cavity. When pouring the casting, the gating end of the sand mold is generally raised to tilt the sand mold at a certain angle to increase the flow rate of the molten steel and facilitate the rapid filling of the sand mold cavity 7. The molten steel is introduced from the gating point at one end and flows a relatively long distance to reach the other end. In order to avoid defects such as porosity and impurities on the casting formed after the molten steel initially entering the sand mold cavity 7 solidifies, this application provides a slag collection bag 6 at the lower end of the sand mold cavity 7. The molten steel with a high impurity content that initially flows the farthest distance into the sand mold is collected by the slag collection bag 6, so that it does not become part of the casting. After the molten steel solidifies, it is cut off as a riser to improve the quality of the casting.

[0041] In this embodiment, see Figure 6 The inflation device is positioned above and connected to the slag collection bag 6. The air inlet pipe 9 of the inflation device is positioned on one side of the slag collection bag 6 and connected to the slag collection bag 6. When protective gas is injected into the sand mold cavity 7, the air in the slag collection bag can be discharged, thereby enabling more complete air discharge from the sand mold cavity 7.

[0042] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A casting apparatus for railway frog castings, comprising an upper sand mold (2) and a lower sand mold (1), wherein the upper sand mold (2) and the lower sand mold (1) are used to enclose and form a sand mold cavity (7) for casting the railway frog, characterized in that, The casting device is provided with a gating device (3) and an air filling device at opposite ends. The gating device (3) is used to pour molten metal into the sand mold cavity, and the air filling device is used to fill the sand mold cavity (7) with protective gas to discharge the air in the sand mold cavity (7) to the outside.

2. The casting device for railway frog castings according to claim 1, characterized in that, The inflation device includes an air inlet pipe (9) and an air duct (5). The air inlet pipe (9) extends downward from the upper sand mold (2) into the sand mold cavity (7). The air duct (5) is detachably connected to the air inlet pipe (9) and is used to connect to a protective gas device.

3. The casting apparatus for railway frog castings according to claim 2, characterized in that, The end of the air duct (5) is provided with an air duct end cap (8), which is used to detachably connect to the air inlet pipe (9).

4. The casting apparatus for railway frog castings according to claim 3, characterized in that, The bleed end cap (8) includes a bleed end (81), a connecting end (82) and a connecting cap (83). The bleed end (81) is used to connect to the protective gas device. The connecting end (82) is used to extend into the air inlet pipe (9). The connecting cap (83) is disposed between the bleed end (81) and the connecting end (82). The connecting cap (83) is used to connect the bleed hose (5) to the air inlet pipe (9).

5. The casting apparatus for railway frog castings according to claim 3, characterized in that, The upper sand mold (2) has a countersunk hole (13) surrounding the air inlet pipe (9), and the countersunk hole (13) is used to accommodate the connecting cover (83) on the air intake end cover (8).

6. The casting apparatus for railway frog castings according to claim 2, characterized in that, The inflation device also includes a sealing cover (11), which is used to be installed on the air inlet pipe (9) after the upper sand mold (2) and the lower sand mold (1) are closed, so as to prevent the air outside the sand mold cavity from forming convection with the gate device through the air inlet pipe (9) and absorbing moisture.

7. The casting apparatus for railway frog castings according to claim 2, characterized in that, The inflation device also includes a sealing element (10), which is inserted into the air inlet pipe (9) during the pouring of molten metal to prevent molten steel from flowing out of the air inlet pipe (9).

8. The casting apparatus for railway frog castings according to claim 1, characterized in that, A sealing strip (12) is provided on the contact surface between the upper sand mold (2) and the lower sand mold (1). The sealing strip (12) is arranged along the circumference of the sand mold cavity (7) to improve the sealing performance of the upper sand mold (2) and the lower sand mold (1) after they are closed.

9. The casting apparatus for railway frog castings according to claim 1, characterized in that, The sand mold cavity (7) is provided with a slag collection bag (6) at the end away from the gating device (3).

10. The casting apparatus for railway frog castings according to claim 9, characterized in that, The inflation device is located above the slag collection bag (6) and is connected to the slag collection bag (6).

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