A method for casting an assembled acute-angle high-manganese steel frog casting

Abstract

The application discloses a kind of assembling type acute angle high manganese steel frog casting's casting method, including the following steps: setting the clear riser with the diameter of 150mm, the height of 300mm, the slope of 1:1.5 between the gating system of frog casting mold and the entrance of frog cavity, setting several dark risers in the length direction in the upper mold back groove of frog casting mold, setting direct external chill combination on the lower mold rail top surface of frog casting mold;The frog casting mold arranged is placed in sand box, the pouring end of sand box is raised using iron stand, pouring is carried out with inclination 6 °, pouring temperature is controlled at 1440-1460 ℃, after steel liquid pours full clear riser, when surface liquid drops 1 / 3, it is supplemented 2 times, and 4-5 times of supplementing is carried out at the end of pouring;After pouring, sand box is opened 24 hours, vibration shakeout is carried out, after being placed to room temperature 25 DEG C, the riser heel of clear riser and dark riser is hammered using air hammer, and frog riser is removed.The high quality casting of frog can be realized by the special setting of frog casting mold and pouring, and the internal defects of casting are significantly reduced.

Description

Technical Field

[0001] This invention relates to the field of high manganese steel frog casting, specifically to a casting method for assembled acute-angle high manganese steel frog castings that meets the radiographic testing quality level requirements specified in the AREMA Track Structure Special Specification Standard. Background Technology

[0002] High-manganese steel frogs are railway turnout components. American-made frogs must meet AMERA standards, and the X-ray inspection requirements are a key factor restricting product and market development. However, American-made frogs produced using existing casting methods have numerous internal defects, failing to meet X-ray inspection requirements. These defects primarily include large areas of shrinkage porosity and numerous sand inclusions within the mold cavity, resulting in excessively high defect levels during X-ray inspection. Shrinkage porosity refers to the formation of scattered, fine pores in the final solidified areas of the casting due to insufficient feeding by liquid metal or alloy. Sand inclusions are caused by sand or other impurities entering the casting during the casting process, resulting in internal inclusions. Summary of the Invention

[0003] To address the shortcomings of the aforementioned technologies, this invention provides a casting method for assembled acute-angle high-manganese steel frog castings that can significantly reduce internal defects in frog castings.

[0004] The technical solution adopted by the present invention to achieve the above-mentioned technical effects is as follows: A casting method for an assembled acute-angle high-manganese steel frog casting, comprising the following steps: S1. Arrange the frog mold. Set an open riser with a bottom diameter of 150mm, a height of 300mm, and a slope of 1:1.5 between the gating system of the frog mold and the frog cavity entrance. Set several hidden risers along the length direction in the upper back groove of the frog mold. Set a direct external chill assembly on the top surface of the lower rail of the frog mold. S2. Place the prepared frog mold in the sand box, use an iron frame to raise the pouring end of the sand box, tilt it at 6° and pour. Control the pouring temperature at 1440~1460℃. After the molten steel fills the open riser, pour twice when the liquid level drops by 1 / 3, and pour 4~5 times at the end of the pouring. S3. After 24 hours of pouring, open the box, shake off the sand, and after it has been cooled to room temperature of 25°C, use an air hammer to hammer the riser base of the open and closed risers to remove the frog risers.

[0005] Preferably, in the above-mentioned casting method for assembled acute-angle high-manganese steel frog castings, the gating system is set at the heel end of the frog mold and includes a pouring cup, a sprue formed at the bottom of the pouring cup, a gating socket formed at the bottom of the sprue, and a transverse gating formed at the heel end of the frog mold. The pouring cup is connected to the transverse gating in sequence through the sprue and the gating socket.

[0006] Preferably, in the above-mentioned casting method for assembled acute-angle high-manganese steel frog castings, the riser is a conical structure with an upper diameter of 150mm and a height of 300mm, and the distance between the center of the riser and the center of the pouring cup is 300mm.

[0007] Preferably, in the above-mentioned casting method for the assembled acute-angle high-manganese steel frog casting, the inner diameter of the riser body of the concealed riser is 180mm, the height is 210mm, the outer diameter of the riser sleeve is 105mm, and the inner diameter is 88mm.

[0008] Preferably, in the above-mentioned casting method for the assembled acute-angle high-manganese steel frog casting, a cylindrical riser support block with a diameter of 100mm and a height of 70mm is placed in the upper back groove of the frog casting mold, and a umbo with a diameter of φ80mm×20mm is placed on the riser support block, and the riser sleeve is positioned and fixed by the umbo.

[0009] Preferably, in the above-mentioned casting method for assembled acute-angle high-manganese steel frog castings, the direct external chill assembly includes a first chill assembly, a second chill assembly, and a third chill assembly. The first chill assembly is located on the side near the heel end of the frog casting mold, the third chill assembly is located on the side near the toe end of the frog casting mold, and the second chill assembly is located at the middle of the top surface of the lower rail of the frog casting mold.

[0010] Preferably, in the above-mentioned casting method for the assembled acute-angle high-manganese steel frog casting, the first chill assembly includes three A-type chill blocks with the same specifications and structure, the third chill assembly includes three A-type chill blocks with the same specifications and structure, and the second chill assembly includes one B-type chill. The length, width, and height dimensions of the A-type chill block are 160×50×40mm, and the length, width, and height dimensions of the B-type chill block are 160×30×40mm.

[0011] Preferably, in the above-mentioned casting method for assembled acute-angle high-manganese steel frog castings, both the type A chill block and the type B chill block are strip-shaped direct external chill blocks with trapezoidal cross-sections.

[0012] The beneficial effects of the present invention are as follows: the casting method of the present invention, through the special setting of the fork mold and the pouring, can realize the high-quality casting of assembled acute-angle high-manganese steel forks, and the internal defects of the obtained fork castings can be significantly reduced, which can fully meet the requirements of the radiographic testing quality level specified in the "AREMA Track Structure Special Specification Standard". Attached Figure Description

[0013] Figure 1 This is a structural diagram of the fork casting described in this invention; Figure 2 This is a plan view of the fork casting described in this invention on the back side of the upper mold. Detailed Implementation

[0014] To provide a further understanding of the present invention, the invention will be further described below with reference to the accompanying drawings and specific embodiments: In the description of this invention, it should be noted that the terms "vertical," "upper," "lower," and "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0015] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or a connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0016] An embodiment of the present invention provides a casting method for an assembled acute-angle high-manganese steel frog casting, the method comprising the following steps: S1. Arrange the frog casting mold, such as Figure 1 and Figure 2 As shown, an exposed riser 1 with a bottom diameter of 150mm, a height of 300mm, and a slope of 1:1.5 is provided between the gating system of the frog mold and the frog cavity inlet. Several concealed risers 2 are provided along the length direction in the upper mold back groove of the frog mold. A direct external chill assembly 3 is provided on the top surface of the lower mold rail of the frog mold. It should be noted that, for ease of clear illustration... Figure 1 and Figure 2 , Figure 1 and Figure 2 In the diagram, the frog casting is shown in a vertical direction, but in actual use, the frog casting is arranged in a horizontal direction.

[0017] Among them, such as Figure 1 As shown, the gating system is located at the heel end of the frog mold and includes a pouring cup 4, a sprue 41 formed at the bottom of the pouring cup 4, a gating recess 42 formed at the bottom of the sprue 41, and a runner 43 formed at the heel end of the frog mold. The pouring cup 4 is connected to the runner 41, the gating recess 42, and the runner 43 in sequence. The pouring cup 4 is used to receive the molten metal poured in from the ladle. The sprue 41 connects the outer gate of the pouring cup 4 to the runner 43 and is used to introduce the molten metal from the outside of the mold into the inside of the mold. The runner 43 connects to the sprue 41 and distributes the molten metal flow entering from the sprue 41.

[0018] Specifically, the exposed riser 1 is a conical structure, wider at the top and narrower at the bottom, with an upper diameter of 150mm and a height of 300mm. The distance between the center of the exposed riser 1 and the center of the pouring cup 4 is 300mm. The riser body 21 of the concealed riser 2 has a diameter of 180mm and a height of 210mm. The riser sleeve 22 has an outer diameter of 105mm and an inner diameter of 88mm. To better secure the riser sleeve 22, such as... Figure 1 As shown, a cylindrical riser support block with a diameter of 100 mm and a height of 70 mm is placed in the upper back groove of the turnout mold. A positioning umbo is placed on the riser support block, and the riser sleeve 22 is positioned and fixed by the umbo. Because the inner diameter of the riser sleeve 22 is 88 mm, a margin needs to be left. At the same time, if the umbo is too large, it will cause inaccurate positioning. Therefore, the umbo is made with a diameter of φ80 mm and a height of 20 mm.

[0019] S2. Place the prepared turnout mold in the sand box, elevate the pouring end of the sand box using an iron frame, and pour at a 6° angle. Control the pouring temperature at 1440~1460℃. After the molten steel fills the open riser 1, pour twice more when the liquid level drops by 1 / 3, and then pour 4~5 more times at the end of the pouring process. Specifically, pouring at a 6° angle results in a more stable filling process, which is conducive to the discharge of gas in the mold cavity, reduces the proportion of the gating system, improves alloy utilization, and the temperature gradient from bottom to top is beneficial to the riser's feeding, resulting in a more reasonable solidification sequence. However, if the tilt angle is too large, it will cause excessive impact of the molten metal on the sand mold, damaging the sand mold and affecting product quality. Through multiple experiments, it was found that an tilt angle of about 6° is the optimal pouring angle. Practice has shown that forks cast at a pouring temperature of 1440~1460℃ are of higher quality. Because high manganese steel has a high linear shrinkage rate, insufficient molten steel during the resolidification process can easily produce large voids. Therefore, it is necessary to strengthen the replenishment of molten steel and increase the amount of molten steel. Practice has shown that strengthening the replenishment of molten steel 4 to 5 times at the end of the pouring process can further reduce the internal defects of the fork casting.

[0020] S3. After pouring, open the box 24 hours later, shake off the sand, and after it has been cooled to room temperature of 25°C, use an air hammer to hammer the riser base of open riser 1 and closed riser 2 to remove the frog riser.

[0021] Furthermore, in a preferred embodiment of the present invention, such as Figure 1 As shown, the direct external chill assembly 3 includes a first chill assembly 31, a second chill assembly 32, and a third chill assembly 33. The first chill assembly 31 is located near the heel end of the frog mold, the third chill assembly 33 is located near the toe end of the frog mold, and the second chill assembly 32 is located at the center of the top surface of the lower rail of the frog mold. Specifically, the first chill assembly 31 includes three A-type chill blocks of identical specifications and structure, the third chill assembly 33 includes three A-type chill blocks of identical specifications and structure, and the second chill assembly 32 includes one B-type chill. In a preferred embodiment of the invention, the length, width, and height dimensions of the A-type chill block are 160×50×40mm, and the length, width, and height dimensions of the B-type chill are 160×30×40mm. Both the A-type and B-type chill blocks are trapezoidal strip-shaped direct external chills.

[0022] The chill block is 40mm thick, and the maximum wall thickness at this location is 55mm. Calculations show that the chill block thickness needs to be at least 38mm to achieve sequential solidification. Therefore, the height of the chill block is chosen to be 40mm, with 30mm and 50mm being the maximum width required for the desired location. If the chill block is too heavy, it will fall off during the flipping process. Through stress analysis, friction calculation, and sand mold strength calculation, it is determined that the chill block should be less than 160mm long. The trapezoidal cross-section is also to increase the friction of the chill block in the sand mold.

[0023] In an embodiment of the invention, radiographic inspection of American-assembled frogs is used to determine the areas of the frog casting that require feeding. Analysis of the defects at these areas determines the volume that needs feeding. During the cooling and solidification process of molten metal, the volume shrinks. The volume shrinkage of a casting is approximately three times its linear shrinkage. Therefore, the volume shrinkage of cast steel is typically considered to be 3-6%. Riser-feeding castings have a certain effective feeding distance, or effective feeding distance. The effective feeding distance L of a riser-feeding casting for a plate-shaped casting with thickness h is related to the thickness h of the plate-shaped casting as: L = 3-5h. The riser sleeve is determined by calculating the riser modulus and the amount of molten metal required for feeding the casting. In the embodiment of the present invention, the riser sleeve 22 is a heat-generating and heat-insulating riser sleeve. As an important casting supporting material, it is mainly used to protect the riser from the influence of the external environment during the casting process, prevent the penetration and corrosion of molten metal, and extend the service life of the riser. At the same time, it also has the functions of reducing heat loss and improving energy utilization efficiency, saving energy consumption and reducing production costs for casting enterprises.

[0024] Specifically, the riser diameter D = d0 + h, where h is the thickness of the plate-shaped casting. When a hot spot exists in the casting, h can be replaced with the diameter T of the hot spot, i.e., D = d0 + T. The riser neck feeding 23 is the connection channel between the riser body 21 and the casting. The molten metal in the riser enters the casting through the riser neck feeding 23. Therefore, there are requirements for the cross-section of the riser neck feeding. Usually, the diameter of the riser neck feeding is taken as dj = (0.6-0.8)T, where T is the diameter of the hot spot. The riser height H = (1.5-2.5)D, where D is the riser diameter. Through calculation, it is found that the inner diameter needs to be greater than 170mm and the height greater than 200mm to ensure feeding at this location. Therefore, the dimensions of the hidden riser 2 are determined as follows: inner dimensions φ180×210mm. In addition, as Figure 1 As shown, from the heel end of the fork mold ( Figure 1 (as shown above) to the toe tip ( Figure 1 In the direction shown at the lower end), the adjacent center distances of the chilled iron blocks set on the top surface of the lower rail of the frog casting mold are 400mm, 270mm, 325mm, 515mm, 580mm, and 480mm, respectively. Figure 2 As shown, from the heel end of the fork mold ( Figure 2 (as shown above) to the toe tip ( Figure 2 In the direction shown at the lower end, the adjacent center distances of each hidden riser 2 set in the back groove of the upper mold of the fork casting are 500mm, 426mm, 588mm, 520mm, 520mm, and 520mm respectively. This arrangement allows for sequential solidification of the casting at corresponding locations, reducing shrinkage defects within the casting.

[0025] The assembly-type frog casting method of the present invention, through special settings and pouring of the frog mold, can achieve high-quality casting of assembly-type acute-angle high-manganese steel frogs. The internal defects of the obtained frog castings can be significantly reduced, which can fully meet the requirements of the radiographic testing quality level specified in the AREMA Track Structure Special Specification Standard. It can be applied to the casting of various models of American assembly-type acute-angle high-manganese steel frog castings.

[0026] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A casting method for an assembled acute-angle high-manganese steel frog casting, characterized in that, Including the following steps: S1. Arrange the frog mold, and set an open riser with a bottom diameter of 150mm, a height of 300mm, and an inclination of 1:1.5 between the gating system of the frog mold and the frog cavity entrance (1). Set several hidden risers along the length direction in the back groove of the upper mold of the frog mold (2). Set a direct external chill assembly on the top surface of the lower mold rail of the frog mold (3). S2. Place the prepared fork casting mold in the sand box, use an iron frame to raise the pouring end of the sand box, tilt it at 6° for pouring, control the pouring temperature at 1440~1460℃, after the molten steel fills the open riser (1), pour twice when the liquid level drops by 1 / 3, and pour 4~5 times at the end of the pouring period. S3. After 24 hours of pouring, open the box, shake off the sand, and wait until the temperature reaches 25°C. Then, use an air hammer to hammer the roots of the open riser (1) and the closed riser (2) to remove the frog riser. The gating system is set at the heel end of the fork mold and includes a gating cup (4), a sprue (41) formed at the bottom of the gating cup (4), a gating socket (42) formed at the bottom of the sprue (41), and a gating sprue (43) formed at the heel end of the fork mold. The gating cup (4) is connected to the gating sprue (43) in sequence through the sprue (41) and the gating socket (42). The direct external chill assembly (3) includes a first chill assembly (31), a second chill assembly (32) and a third chill assembly (33). The first chill assembly (31) is located on one side near the heel end of the frog casting, the third chill assembly (33) is located on one side near the toe end of the frog casting, and the second chill assembly (32) is located at the middle of the top surface of the lower rail of the frog casting. The first chill assembly (31) includes three A-type chill blocks with the same specifications and structure. The third chill assembly (33) includes three A-type chill blocks with the same specifications and structure. The second chill assembly (32) includes one B-type chill block. The length, width and height of the A-type chill block are 160×50×40mm. The length, width and height of the B-type chill block are 160×30×40mm. From the heel end to the toe end of the fork casting, the adjacent center distances of the chilled iron blocks set on the top surface of the lower rail of the fork casting are 400mm, 270mm, 325mm, 515mm, 580mm, and 480mm respectively. From the heel end to the toe end of the fork casting, the adjacent center distances of each hidden riser (2) set in the back groove of the upper mold of the fork casting are 500mm, 426mm, 588mm, 520mm, 520mm and 520mm respectively.

2. The casting method for the assembled acute-angle high-manganese steel frog casting according to claim 1, characterized in that, The riser (1) is a conical structure with an upper diameter of 150 mm and a height of 300 mm. The distance between the center of the riser (1) and the center of the pouring cup (4) is 300 mm.

3. The casting method for the assembled acute-angle high-manganese steel frog casting according to claim 1, characterized in that, The riser body (21) of the dark riser (2) has an inner diameter of 180 mm and a height of 210 mm, and the riser sleeve (22) has an outer diameter of 105 mm and an inner diameter of 88 mm.

4. The casting method for the assembled acute-angle high-manganese steel frog casting according to claim 3, characterized in that, A cylindrical riser support block with a diameter of 100 mm and a height of 70 mm is placed in the back groove of the upper mold of the turnout casting. A umbo with a diameter of φ80 mm × 20 mm is placed on the riser support block. The riser sleeve (22) is positioned and fixed by the umbo.

5. The casting method for the assembled acute-angle high-manganese steel frog casting according to claim 1, characterized in that, Both the Type A chill and the Type B chill are strip-shaped direct external chills with a trapezoidal cross-section.

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