A method of casting an exhaust cylinder casting

Abstract

The present application belongs to the field of casting technology, and mainly relates to a casting method of exhaust cylinder casting, comprising the following steps: adopting a vertical integral casting mode, a rib plate is arranged at the lower part; an actual sample mold is used to form the edge part of the rib plate; sand cores are used to form the remaining part of the edge of the rib plate, the joint cylinder part and the exhaust hole, and the integral sand core formed by the sand cores and the sand mold formed by the actual sample mold are combined to form a casting cavity. The casting method provided by the present application can effectively reduce the process operation difficulty, greatly improve the production efficiency, and significantly improve the quality of the casting.

Description

Technical Field

[0001] This invention belongs to the field of casting technology, and mainly relates to a casting method for exhaust cylinder castings. Background Technology

[0002] In the design of the casting process for the exhaust cylinder of a large gas turbine compressor, the upper and lower halves of the cylinder body are generally cast vertically as a single unit. Due to the slender structure of the ribs and the wall thickness being less than that of the connecting flanges, dimensional accuracy is difficult to control, making direct molding with a physical mold impossible. Instead, sand cores are typically used at the rib areas. On one hand, the process design divides the sand core area based on the center of each rib, using a positioning core head and jig for core placement. While this simplifies the core-making process, it has significant limitations and increases the difficulty. Furthermore, the large number of sand cores leads to a large cumulative error in the gaps between them during core assembly, ultimately affecting the dimensions of the casting ribs. On the other hand, because the upper and lower halves of the exhaust cylinder are designed with a cylinder-joining patch, the combined casting becomes elliptical. To maintain the consistency of the sand core and mold structure around the external ribs of the upper and lower halves, a separate partition core is set at the cylinder-joining reference area. Compared to other sand cores in the casting, the partition core is an auxiliary sand core in the forming process and does not form the casting structure. This increases the number of sand cores. At the same time, due to its narrow and tall shape, the lower core is prone to sand rubbing and tipping over, which increases the difficulty of operation, reduces the dimensional accuracy of the casting, and cannot guarantee the quality of the casting. Summary of the Invention

[0003] Based on the above problems, it is necessary to propose a casting method for exhaust cylinder castings. This method primarily improves casting quality by rationally dividing the sand core and employing independent positioning between adjacent sand cores. The exhaust cylinder casting includes a cylinder assembly, exhaust ports, and ribs.

[0004] A casting method for an exhaust cylinder casting includes the following steps: a vertical integral casting method is adopted, with the rib plate placed at the bottom; the edge of the rib plate is formed using a sample mold; the remaining part of the rib plate except the edge, the cylinder assembly part and the exhaust hole are formed using sand core assembly, and the integral sand core formed by the core assembly is combined with the sand mold formed by the sample mold to form the casting cavity.

[0005] In one embodiment, the casting method further includes: fabricating an integral sand core, and dividing the integral sand core into several sand core modules based on the cylinder assembly portion of the cylinder casting, the rib portion forming a 90° angle with the cylinder assembly portion, and the remaining rib portion of the casting. Preferably, the lower core gap between each of the sand core modules is 2mm to 3.5mm.

[0006] In one embodiment, the step of making an integral sand core includes making a first sand core, which is used to form the structure of the cylinder assembly, the side part of the rib plate near the mating surface, and half of the exhaust hole near the mating surface.

[0007] In one embodiment, the step of making an integral sand core includes making a second sand core, which is used to form a portion between adjacent stiffeners of the casting that is at a 90° angle to the cylinder assembly.

[0008] In one embodiment, the step of making an integral sand core includes making a third sand core, which is used to form the part of the casting between the first sand core and the second sand core.

[0009] In one embodiment, the casting method further includes: fabricating core heads by fabricating matching core heads according to the structure of each sand core module after the overall sand core is divided; the core assembly sequence is as follows: first, each core head is placed at a position in the sand mold formed by the set sample mold; then, each sand core module is assembled according to the contour of the matching core head to form the casting cavity. In this way, each sand core module can be cored independently, avoiding the cumulative error caused by cored sequentially. Preferably, the shape of each core head is set as a cuboid, which can avoid problems such as tilting and instability of the sand core during the cored process, so as to ensure that each sand core module has good stability.

[0010] The casting method for exhaust cylinder castings provided by this invention adopts a vertical integral casting method and uses a sample mold combined with sand core assembly to form the core, eliminating the need to make a jig and simplifying the forming process. By rationally dividing the sand core and adopting an independent positioning method between adjacent sand cores, the problem of large dimensional deviations in the semi-finished castings caused by poor core precision is effectively improved, thereby improving the dimensional accuracy of the casting ribs. The sand core division method provided by this method reduces the number of sand cores and the amount of loose sand in the sand mold cavity, and avoids problems such as sand flushing during pouring.

[0011] The casting method provided by this invention can effectively reduce the difficulty of process operation, greatly improve production efficiency, and significantly improve the quality of castings. Attached Figure Description

[0012] Appendix Figure 1 This is a schematic diagram of the cylinder casting structure in the embodiment;

[0013] Appendix Figure 2 This is a schematic diagram of the sand core structure in the embodiment;

[0014] Appendix Figure 3 This is a schematic diagram of the second sand core structure in the embodiment;

[0015] Appendix Figure 4 This is a schematic diagram of the three structures of the sand core in the embodiment;

[0016] Appendix Figure 5 This is a schematic diagram of the overall sand core structure in the embodiment.

[0017] 10 - Cylinder assembly area; 20 - Rib plate; 30 - Exhaust port; 40 - Sand core one; 50 - Sand core two; 60 - Sand core three. Detailed Implementation

[0018] To facilitate understanding of the present invention, a more complete description is provided below, along with preferred embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0019] This embodiment mainly relates to a casting method for a large gas turbine compressor exhaust cylinder casting. The exhaust cylinder casting includes a cylinder assembly 10, a rib 20, and an exhaust port 30. See attached drawing. Figures 1 to 5 As shown, the casting method specifically includes the following steps:

[0020] 1. The vertical integral casting method is adopted, with the rib plate 20 placed at the bottom; the edge of the rib plate 20 is formed by a sample mold; the remaining part of the rib plate 20 except the edge, the cylinder part 10 and the vent hole 30 are formed by sand core assembly, and the integral sand core formed by the core assembly is combined with the sand mold formed by the sample mold to form the casting cavity.

[0021] Since the casting rib plate 20 is a slender and easily deformable structure, and the casting cylinder assembly part 10 is designed with a narrow space after the cylinder assembly patch, it is not possible to use a full-size mold for shaping. It is preferable to use a full-size mold combined with a sand core assembly for shaping. The shape of the edge part of the casting rib plate 20 (30mm from the outer end of the rib plate inward) is formed by the full-size mold, while the other parts of the rib plate that connect to the outer wall of the casting, the cylinder assembly part, and the vent hole above the rib plate are all formed by the sand core assembly.

[0022] 2. Make integral sand cores. Divide the integral sand core into several sand core modules according to the cylinder assembly part 10, the rib plate part that is 90° to the cylinder assembly part 10, and the remaining rib plate part of the casting.

[0023] 3. Fabricate each sand core module. Each sand core module includes two sand cores 40, two sand cores 50, and four sand cores 60. Sand core 40 is used to form the structure of the cylinder assembly part, the side part of the rib plate near the joint surface, and half of the vent hole near the joint surface. Sand core 50 is used to form the part between adjacent rib plates of the casting that is at a 90° angle to the cylinder assembly part. Sand core 60 is used to form the part of the casting between sand cores 40 and 50, specifically the outer contour of this part, a vent hole adjacent to it, and the side part adjacent to the rib plate.

[0024] 4. Fabricate core heads: Based on the structure of each sand core module after the overall sand core is divided, fabricate matching core heads. The core assembly sequence is as follows: first, place each core head on the designated position of the sand mold formed by the sample mold; then, assemble each sand core module according to the outline of the matching core head to form the casting cavity. The shape of each core head can be set as a cuboid to avoid problems such as tilting and instability of the sand core during the core setting process, thus ensuring good stability of each sand core module. The core setting gap between each sand core module is 2mm to 3.5mm to ensure sufficient space for core setting even if the sand core expands or the outer mold deforms slightly, while avoiding excessive core gaps.

[0025] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0026] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A casting method for an exhaust cylinder casting, characterized in that, The exhaust cylinder casting includes a cylinder assembly part, an exhaust port, and ribs. The casting method includes the following steps: a vertical integral casting method is adopted, with the ribs placed at the bottom; the edge of the ribs is formed using a sample mold; the remaining part of the ribs except the edge, the cylinder assembly part, and the exhaust port are formed using sand core assembly, and the integral sand core formed by the core assembly is combined with the sand mold formed by the sample mold to form the casting cavity; the integral sand core is made by dividing the integral sand core into several sand core modules according to the cylinder assembly part, the rib part that is 90° to the mating surface of the cylinder assembly part, and the remaining rib part of the casting, including making sand core one, which is used to form the structure of the cylinder assembly part, the side part of the rib near the mating surface, and half of the exhaust port near the mating surface; making sand core two, which is used to form the part between adjacent ribs of the casting that is 90° to the cylinder assembly part; and making sand core three, which is used to form the part of the casting between sand core one and sand core two.

2. The casting method for the exhaust cylinder casting according to claim 1, characterized in that, The casting method further includes: making core heads, and making matching core heads according to the structure of each sand core module after the overall sand core is divided; the order of core assembly is as follows: first, each core head is set in the part of the sand mold formed by the set sample mold, and then each sand core module is assembled according to the outline of the matching core head to form the casting cavity.

3. The casting method for the exhaust cylinder casting according to claim 2, characterized in that, Each of the described cores is shaped as a cuboid.

4. The casting method for the exhaust cylinder casting according to claim 1, characterized in that, The gap between the lower cores of each of the aforementioned sand core modules is 2mm to 3.5mm.

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