Train coupler casting method based on precoated sand shell mold and shell mold structure

Abstract

The invention provides a train coupler casting method based on a precoated sand shell mold and a shell mold structure, and belongs to the technical field of ferrous metal casting, and the shell mold structure comprises a mold shell, an outer chilling block, an exothermic riser, an anti-scouring pouring gate, a core, an exhaust cap and an assembling method thereof. Wherein the mold shell comprises an outer shell assembly and an inner shell assembly, and the thickness of the outer shell assembly is larger than that of the inner shell assembly; the shell is further characterized by a hollow structure of a local thick and large part, an ox horn type flow gate and a cavity exhaust structure. The outer shell assembly is used for forming the outer shape of the coupler body, the inner shell assembly is used for forming the hollow part of the coupler body, and the characteristics of the coupler body casting mold are beneficial to obtaining the coupler body casting with high dimensional precision and good surface quality and internal quality, reducing the adverse effect of resin gas generation on the product, reducing the influence factor of shrinkage blocking, and improving the production efficiency. And the tendency of air holes and cracks of the casting is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of ferrous metal casting, and particularly relates to a casting method for a train coupler based on a coated sand shell mold and a shell mold structure. Background Art

[0002] As an important connecting component of railway vehicles, the quality and performance of train couplers directly affect the operation safety of trains. To meet the requirements of high-speed and heavy-haul railway transportation, train couplers will develop in the direction of high strength, high reliability, and high safety, and the materials and manufacturing processes will be continuously improved to increase the service life and performance of couplers. As the core component of train couplers, the traditional casting process for the coupler body is water glass sand molding, which has problems such as poor surface quality, low dimensional accuracy, many hole defects such as sand holes, and especially high labor intensity for workers. Summary of the Invention

[0003] The purpose of the present invention is to provide a casting method for a train coupler based on a coated sand shell mold and a shell mold structure, aiming to solve the problems in the prior art such as poor surface quality, low dimensional accuracy, many hole defects such as sand holes, and especially high labor intensity for workers.

[0004] To achieve the above purpose, the present invention provides the following technical solution: A shell mold structure, comprising: a shell mold and a core. The shell mold includes an outer shell assembly and an inner shell assembly. It is characterized in that the outer shell assembly is used to form the external shape of the coupler body, the inner shell assembly is used to form the hollow part of the coupler body, the thickness of the outer shell assembly is greater than that of the inner shell assembly, and it further includes: A thick and large part provided on the shell mold. The thick and large part adopts a hollow structure, and a cover is provided at the hollow part to prevent molten steel from flowing out of the mold cavity. Exothermic risers. The exothermic risers are provided on the outer shell assembly. There are multiple exothermic risers, and a positioning structure cooperating with the exothermic risers is provided on the shell mold for the assembly positioning of the exothermic risers. External chillers, which are provided on the inner shell assembly and the outer shell assembly and are located at the hot spots of the castings of the inner shell assembly and the outer shell assembly. The external chillers are fixed during the sand shooting of the inner shell assembly and the outer shell assembly, and are used to increase the solidification speed of the local hot spots of the castings. A gating system, which is connected to the cavity of the shell mold, is used to guide molten steel into the cavity and can fill the cavity with molten steel. An exhaust system assembly, which is provided on the shell mold, is used to discharge the gas generated inside the cavity and in the inner shell assembly. An exhaust cap is provided on the exhaust system assembly to prevent steel shot from entering the cavity.

[0005] A further technical solution of the present invention is that the outer shell assembly includes an upper outer shell and a lower outer shell, and the upper outer shell and the lower outer shell can be spliced to form a complete outer shell assembly. The inner shell assembly includes an upper inner shell and a lower inner shell, and the upper inner shell and the lower inner shell can be spliced to form a complete inner shell assembly.

[0006] A further technical solution of the present invention is that two of the shell molds form a group to constitute a complete casting mold. A sprue, a runner and an ingate are arranged between the two shell molds. The sprue and the runner are made of erosion-resistant materials. The shape of the ingate is in the shape of a horn, and the flared end thereof is close to the coupler body of the train and is connected to the inside of the mold cavity, and the constricted end is connected to the inside of the runner.

[0007] A further technical solution of the present invention is that the exhaust system assembly includes a cavity exhaust passage and an inner shell exhaust passage. The cavity exhaust passage is located at the relatively high point of the upper casting and is connected to the inside of the cavity. The exhaust cap is installed on the cavity exhaust passage. The inner shell exhaust passage is arranged on the inner shell assembly for discharging the gas generation amount of the inner shell assembly.

[0008] A further technical solution of the present invention is that it further includes a fixing tooling for assembling and fixing the complete casting mold.

[0009] A method for casting a train coupler based on a coated sand shell mold, characterized by comprising the following steps: S1. Assembly of external chill: Embed a plurality of external chills and position them at the local hot spots of the casting. After sand shooting, fix the external chills on the shell mold. S2. Preparation stage of the shell mold: Use a coated sand shell core machine to separately manufacture an outer shell assembly, an inner shell assembly, a cover and a plurality of cores. When manufacturing the inner shell assembly, a hollow structure is adopted for the thick and large parts. S3. Assembly of the gating system: Connect the sprue, the runner and the ingate, connect the ingate to the shell mold, and fix them through the fixing tooling. S4. Assembly of cores, exothermic risers and covers: Install a plurality of cores, casting letter cores and exothermic risers on the inner shell assembly and the outer shell assembly in a specified order. Fix the cores and the casting letter cores on the shell mold through the fixing tooling. The exothermic risers are fixed on the shell mold with a special adhesive. The cover is fixed at the hollow structure with a special adhesive. S5. Design of the exhaust system assembly: Design an exhaust system assembly on the shell mold and plug the opening with an exhaust cap to ensure that the steel shot cannot enter but the gas can be discharged. S6. Steel shot filling and ramming operation: Bury the fixed shell mold in the steel shot and ram it. S7. Pouring and cooling of the casting: Pour the molten metal into the shell mold. After the molten metal solidifies in the shell mold, take out the casting and cool it.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. By designing a hollow structure to reduce the overall thickness of the shell mold, the gas evolution amount of the shell mold during pouring can be significantly reduced. Compared with the traditional sodium silicate sand molding, the gas evolution amount of the coated sand shell mold is larger. At the same time, the reduction of the shell mold thickness also enhances its collapsibility, avoiding the formation of defects such as casting cracks. Setting the thickness of the outer shell component to be greater than that of the inner shell component can ensure that the overall shell mold has sufficient structural strength. At the same time, the relatively thinner inner shell component helps to improve its collapsibility. Through the designed thickness difference, not only the overall structural stability of the shell mold is enhanced, but also the quality and reliability of the casting are significantly improved.

[0011] 2. The inner runner is designed with a horn-shaped structure. When the molten steel transitions from the neck-down to the neck-up area, due to the change in the flow cross-section, the flow rate of the molten steel naturally slows down, reducing the direct scouring force of the molten steel on the inner wall of the shell mold, and effectively reducing the shell mold wear problem caused thereby. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention. In the drawings: Figure 1 is a schematic structural diagram of the outer shell component in a specific embodiment of the present invention; Figure 2 is an axonometric schematic diagram of the coupler body of a train coupler in a specific embodiment of the present invention; Figure 3 is a bottom view of the coupler body of a train coupler in a specific embodiment of the present invention; Figure 4 is Figure 1 an enlarged schematic diagram of the structure at A in Figure 5 is a schematic structural diagram of the inner shell component in a specific embodiment of the present invention; Figure 6 is a schematic structural diagram of the thick and large part in a specific embodiment of the present invention.

[0013] In the drawings: 11. Outer shell component; 111. Installation groove; 112. Riser neck; 113. Protrusion structure; 114. Upper outer shell; 115. Lower outer shell; 12. Inner shell component; 121. Upper inner shell; 122. Lower inner shell; 13. Thick and large part; 14. Cover; 2. Sprue; 3. Inner runner; 31. Upper inner runner shell; 32. Lower inner runner shell; 4. Exothermic riser; 51. Cavity exhaust channel; 52. Inner shell exhaust channel; 6. Exhaust cap; 7. External chills; 8. Pouring cup; 9. Cross runner. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0015] Please refer to Figures 1-6 , the present invention provides the following technical solutions: a shell-type structure, including a shell mold, and a gating system connected to the shell mold. The shell mold is designed to cast and form a train coupler body separately; The shell mold is composed of an outer shell assembly 11 and an inner shell assembly 12. The outer shell assembly 11 is specifically composed of an upper outer shell 114 and a lower outer shell 115 spliced together, and its internal cavity constitutes the external contour of the train coupler body. Correspondingly, the inner shell assembly 12 is composed of an upper inner shell 121 and a lower inner shell 122 spliced together, and its outer wall defines the hollow structure inside the body of the train coupler. Through the combination of the outer shell assembly 11 and the inner shell assembly 12, the two together define a casting cavity reflecting the shape of the train coupler body. Therefore, each shell mold is equipped with such an independent cavity, ensuring that a complete train coupler body casting can be formed in a single casting. After that, the upper outer shell 114 and the lower outer shell 115, as well as the upper inner shell 121 and the lower inner shell 122, are fixed together by a fixing tooling (not shown in the figure) to form a complete and stable shell mold.

[0016] Here, it should be added that a fixing tooling (not shown in the figure) is used to combine and firmly fix the outer shell assembly 11 and the inner shell assembly 12 into a whole shell mold, while ensuring that the seams between the shell molds are tight to effectively prevent the molten metal from leaking during the pouring process. In addition, the fixing tooling is also used to assemble and fix the shell molds of two castings together to form a complete casting mold. These fixing toolings include but are not limited to tools such as iron wires, slot-type fitting structures, reusable bolts, buckles, or fixing jigs specially designed according to the shape of the shell mold. For example, the shell molds are tied with iron wires.

[0017] In the shell mold, for the thick and large part 13 of the shell, a hollow structure is adopted, aiming to effectively reduce the overall thickness of the shell mold. This hollow structure can be formed during the shell-making process. After that, a cover 14 is installed at the open end of the hollow structure. The cover 14 is also manufactured by a coated sand shell core machine. The finished cover 14 is fixed by a fixing tooling, and the positions that cannot be fixed are firmly bonded with a special adhesive to ensure the sealing performance at the opening of the hollow structure, thereby preventing the molten steel from leaking from the opening during the pouring process.

[0018] By designing a hollow structure to reduce the overall thickness of the shell mold, not only can the gas evolution amount of the shell mold during pouring be significantly reduced, effectively preventing defects such as bubbles in the casting of the train coupler body caused by gas retention; at the same time, the reduction of the shell mold thickness also enhances its collapsibility, which greatly alleviates the internal shrinkage stress during the solidification of the casting, effectively avoiding the formation of defects such as casting cracks, and thus significantly improving the overall quality and reliability of the casting. In addition, it also effectively reduces the shell mold manufacturing cost.

[0019] During the manufacturing process of the outer shell component 11 and the inner shell component 12, the thickness of the outer shell component 11 is set to be greater than that of the inner shell component 12. The thickening of the outer shell component 11 is to ensure that the overall shell mold has sufficient structural strength. At the same time, the relatively thinner inner shell component 12 helps to improve its collapsibility, and can reduce defects such as cracks generated by internal stress concentration during the solidification of the casting. Through the designed thickness difference, not only the overall structural stability of the shell mold is enhanced, but also the quality and reliability of the casting are significantly improved, ensuring the excellent performance of the final product.

[0020] In a complete mold, it includes a pair of shell molds arranged in rotational symmetry, and a gating system for connecting this pair of shell molds. The gating system is divided into three parts: the sprue 2, the runner 9, and the ingate 3. The sprue 2 is a tubular structure perpendicular to the ground, and its top is equipped with a funnel-shaped pouring cup 8. The necked end of the pouring cup 8 is tightly connected to the upper port of the sprue 2. This design aims to optimize the introduction process of the molten steel to ensure that the molten steel can smoothly and accurately enter the internal space of the sprue 2.

[0021] The bottom of the sprue 2 is connected to the runner 9 by splicing or integrally formed, and their internal channels are interconnected, forming a continuous and smooth molten steel flow path. The end of the runner 9 far from the sprue 2 is connected to the ingate 3 by splicing, and their internal channels are interconnected. It should be noted that the ingate 3 is further divided into two components: the upper ingate shell 31 and the lower ingate shell 32. Among them, the upper ingate shell 31 is integrally formed when manufacturing the upper outer shell 114, and the lower ingate shell 32 is formed synchronously when manufacturing the lower outer shell 115. When the upper outer shell 114 and the lower outer shell 115 are spliced, the upper ingate shell 31 and the lower ingate shell 32 are perfectly docked to jointly form a complete ingate 3 structure. The inner cavity of this ingate 3 is interconnected with the internal chamber of the outer shell component 11 to ensure unobstructed flow of the molten steel during the casting process.

[0022] In actual operation, the molten steel is first accurately introduced into the sprue 2 via the pouring cup 8, and then smoothly flows through the runner 9 and the ingate 3 under the action of gravity. Finally, it fully fills the internal space of the outer shell assembly 11 until it is completely full, and cooperates with the inner shell assembly 12 to finally solidify into a solid casting with the precise shape of a train coupler body.

[0023] The sprue 2 and the runner 9 are made of materials with erosion resistance properties. Such materials can be selected as ceramic tubes or refractory brick tubes, etc., aiming to effectively resist the erosion of the molten steel during the pouring process, and thus ensure the stability and durability of the sprue 2 under the erosion of the molten steel. The ingate 3 is designed with a horn-shaped structure. Among them, its flared end is adjacent to the train coupler body component and is connected to the inside of the mold cavity; while the tapered end is connected to the inside of the sprue 2. When the molten steel transitions from the tapered end to the flared area, due to the change in the flow cross-section, the flow rate of the molten steel naturally slows down. This design not only significantly reduces the direct erosion force of the molten steel on the inner wall of the mold shell, but also effectively reduces the mold shell wear problem caused thereby, improving the efficiency of the overall casting process and the quality of the casting.

[0024] At the positions where the outer shell assembly 11 needs feeding, a riser positioning structure is provided. The positioning structure includes 4 to 5 integrated mounting grooves 111, and the feeding risers 4 are installed in these mounting grooves 111. A raised structure 113 is provided at the edge of each mounting groove 111, which plays a role in accurately positioning the feeding riser 4, ensuring the stability and accuracy of the feeding riser 4 during the installation process. At the position of the feeding riser 4 of the outer shell assembly 11, a feeding riser easy-to-cut piece is integrally formed to reduce the connection strength between the feeding riser 4 and the coupler casting body, making it easier to separate from the casting body, thus avoiding damaging the casting body. Subsequently, the feeding riser 4 is firmly bonded with a special adhesive to enhance the reliability and tightness of its connection.

[0025] It should be noted that a riser neck 112 directly communicating with the inside of the mold cavity is also configured inside each mounting groove 111. In addition, for the adopted feeding riser 4, this characteristic significantly extends the solidification time of the molten steel, and the feeding time is extended, thereby improving the density and quality of the casting.

[0026] It should be noted that the feeding riser is a mature and widely used existing technology, and can be obtained through conventional market channels. Given that the selection of its shape and materials already belongs to the category of general knowledge in the industry and is not the core of this innovation point, therefore, the specific shape of the feeding riser and the materials used will not be elaborated in detail.

[0027] An exhaust system assembly is arranged on the housing assembly 11. The exhaust system assembly is composed of a cavity exhaust passage 51 and an inner housing exhaust passage 52. The cavity exhaust passage 51 is arranged at a relatively high point position of the housing assembly 11 to ensure that the gas inside the mold cavity can be discharged quickly and efficiently. In order to effectively prevent impurities such as steel shot from entering the exhaust system assembly and ensure the smooth discharge of gas, a special exhaust cap 6 is installed at the open end of the cavity exhaust passage 51. The inner housing exhaust passage 52 is arranged on the inner housing assembly 12, and one end penetrates to the outside of the housing assembly 11, so that the gas generated by the inner housing assembly 12 is completely discharged through the inner housing exhaust passage 52, which is used to reduce the gas evolution of the inner housing assembly 12, thereby reducing the risk of porosity generation.

[0028] The exhaust cap 6 is in a barrel shape and is buckled at the opening of the cavity exhaust passage 51. This design not only realizes the functional requirements of gas discharge, but also ensures the cleanliness and safety of the exhaust system assembly, achieving the technical purpose that steel shot cannot invade and gas can escape freely. And the inner housing exhaust passage 52 can choose whether to install the exhaust cap 6 according to requirements.

[0029] A casting method of a train coupler based on a coated sand shell mold includes the following steps: S1. Assembly of external chill: 30 external chills 7 are pre-positioned and embedded. The 30 external chills 7 are respectively positioned at local hot spots of the casting, and then the external chills 7 are firmly fixed on the shell mold through the sand shooting process to accelerate the solidification speed of local positions of the casting; S2. Shell mold preparation stage: Use a coated sand shell core machine to manufacture the housing assembly 11, the inner housing assembly 12, the cover 14 and multiple cores. When manufacturing the inner housing assembly 12, for the thick and large part 13, a hollow structure design is adopted, which can reduce the shell mold manufacturing cost and increase the collapsibility of the shell mold; S3. Assembly of gating system: Connect the sprue 2, the runner 9 and the ingate 3. The ingate 3 is connected to the shell mold, and the connection is bonded with a fixing tool or special adhesive to ensure the smooth flow of the molten metal and the overall stability of the gating system; S4. Assembly of cores, exothermic risers and covers: Install 7 cores, casting letter cores and exothermic risers 4 on the inner housing assembly 12 and the housing assembly 11 in a specified order, so that the 7 cores form multiple hole structures on the coupler body. The cores and casting letter cores are fixed on the shell mold by a fixing tool, and the exothermic riser 4 is fixed on the shell mold with a special adhesive. At the same time, the cover 14 is also installed at the hollow structure and is also fixed with a special adhesive to ensure the stability and integrity of each component during the casting process; S5. Integrated Design of Exhaust System: Design an integrated exhaust system on the shell mold, and then use the exhaust cap 6 to block the channel openings. This design ensures that the steel shots cannot enter the integrated exhaust system while ensuring the smooth discharge of the gases generated during the casting process, thus avoiding the occurrence of casting defects; S6. Steel Shot Filling and Tamping Operations: Bury the fixed shell mold in the steel shots and tamp the steel shots through a vibration device to ensure that the shell mold is fully supported and protected during the casting process; S7. Pouring and Casting Cooling: Pour the molten steel into the shell mold. After the casting solidifies and cools, and when the cooling time meets the requirements, shake out the sand and remove the casting.

Claims

1. A shell structure comprising: A shell and a core, the shell comprising an outer shell component (11) and an inner shell component (12), characterized in that the outer shell component (11) is used to form the outer shape of the hook body, the inner shell component (12) is used to form the hollow part of the hook body, the outer shell component (11) is thicker than the inner shell component (12), and further comprising: A thick portion (13) is provided on the mold shell, wherein the thick portion (13) adopts a hollow structure, and a cover (14) is provided at the hollow portion to prevent molten steel from flowing out of the mold cavity; A heat-generating riser (4), the heat-generating riser (4) being arranged on the outer shell component (11), a plurality of the heat-generating risers (4) being arranged, and a positioning structure cooperating with the heat-generating riser (4) being arranged on the shell for assembling and positioning the heat-generating riser (4); An external chiller (7) is arranged on the inner shell component (12) and the outer shell component (11) and is located at a hot spot of the casting of the inner shell component (12) and the outer shell component (11). The external chiller (7) is fixed when the inner shell component (12) and the outer shell component (11) are sandblasted to increase the solidification speed of the local hot spot of the casting; A pouring system is connected to the mold shell cavity and is used to guide the molten steel into the cavity and fill the cavity with the molten steel; An exhaust system assembly is arranged on the mold shell and is used to exhaust the gas generated inside the mold cavity and the inner shell component (12). An exhaust cap (6) is arranged on the exhaust system assembly and is used to prevent steel shots from entering the mold cavity.

2. A shell-type structure according to claim 1, characterized in that: The outer shell component (11) comprises an upper outer shell (114) and a lower outer shell (115), and the upper outer shell (114) and the lower outer shell (115) can be spliced ​​together to form a complete outer shell component (11); the inner shell component (12) comprises an upper inner shell (121) and a lower inner shell (122), and the upper inner shell (121) and the lower inner shell (122) can be spliced ​​together to form a complete inner shell component (12).

3. A shell-type structure according to claim 2, characterized in that: The two shells are a group to form a complete casting mold. A sprue (2), a runner (9) and an ingrate (3) are arranged between the two shells. The sprue (2) and the runner (9) are made of erosion-resistant materials. The ingrate (3) is shaped like a bull horn, with one end of the flared opening close to the hook body of the train coupler and connected to the inside of the mold cavity, and the other end of the flared opening connected to the inside of the runner (9).

4. A shell-type structure according to claim 3, characterized in that: The exhaust system assembly comprises a cavity exhaust channel (51) and an inner shell exhaust channel (52); the cavity exhaust channel (51) is located at a relatively high point of the upper casting and is connected to the interior of the cavity; the exhaust cap (6) is mounted on the cavity exhaust channel (51); and the inner shell exhaust channel (52) is arranged on the inner shell component (12) and is used to exhaust the gas generated by the inner shell component (12).

5. A shell-type structure according to claim 4, characterized in that: Also included is a fixing tool, which is used to fix the complete casting mold assembly.

6. A method for casting a train coupler based on a coated sand shell mold, characterized in that: The shell structure as claimed in claim 5 comprises the following steps: S1. External cooling iron assembly: multiple external cooling irons (7) are pre-buried and positioned at local hot spots of the casting, and the external cooling irons (7) are fixed to the mold shell after sand blasting; S2, shell preparation stage: using a coated sand shell core machine to respectively manufacture an outer shell component (11), an inner shell component (12), a cover (14) and a plurality of cores. When manufacturing the inner shell component (12), a thick and large part (13) adopts a hollow structure; S3, assembling the pouring system: connecting the sprue (2), the runner (9) and the ingode (3), connecting the ingode (3) and the mold shell, and fixing them by a fixing tool; S4, assembling the core, the heat riser and the cover: installing a plurality of cores, the casting core and the heat riser (4) on the inner shell component (12) and the outer shell component (11) in a prescribed order, fixing the core and the casting core on the shell by a fixing tool, fixing the heat riser (4) on the shell by a special adhesive, and fixing the cover (14) on the hollow structure by a special adhesive; S5. Exhaust system assembly design: Design an exhaust system assembly on the shell and seal the opening with an exhaust cap (6) to ensure that steel shot cannot enter but gas can be discharged; S6, steel shot filling and compaction operation: bury the fixed shell into the steel shot and compact it; S7. Pouring and cooling of castings: Inject the molten metal into the mold shell. After the molten metal solidifies in the mold shell, take out the casting and cool it.

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