A nozzle ring wax mold assembly process

Abstract

The application discloses a preparation process of a nozzle ring wax mold, which comprises the following steps: wax mold structure design: a 3D model of a patch block on an outer ring is designed; the nozzle ring is equally divided into a plurality of unit segments; mold design; wax mold pressing; wax mold assembly: the pressed unit segment wax molds are sequentially bonded to assemble into an overall wax mold of the nozzle ring, and the wax mold of the patch block is sequentially bonded on the outer ring wax mold according to the hot spot distribution of the blade and the outer ring connecting position through a limiting tool; after wax finishing, the wax mold is assembled with a pouring system; the application independently sets the patch block at the R hot spot of the transition of the outer ring and the blade, reduces the casting stress, reduces the risk of cracks, controls the size deformation, improves the casting qualification rate of the nozzle ring, greatly improves the process yield, improves the production efficiency, saves the production cost, can accurately position the patch block at the hot spot position, can quickly weld the patch block, and improves the efficiency of industrial batch production.

Description

Technical Field

[0001] This invention relates to the field of investment casting technology, and in particular to a nozzle ring wax mold assembly process. Background Technology

[0002] Gas turbines require nozzle rings to adjust airflow direction. The nozzle ring is a crucial component of the gas turbine, needing to maintain overall precision while also ensuring the installation and casting accuracy of the blades. (e.g., nozzle ring...) Figure 1 The nozzle ring (shown) has an inner and outer ring structure. The inner ring 1 and the outer ring 2 are connected by multiple blades 3. The blades in the existing nozzle ring are fixed to the inner and outer rings and are formed by one-time casting. To obtain a high-precision nozzle ring during the casting process, highly complex casting techniques and specialized equipment are required. The nozzle ring has a complex structure with significant differences in wall thickness and small blade cross-sections. During solidification, defects such as incomplete filling, porosity, and cracks are easily generated. Furthermore, the nozzle ring operates under harsh conditions, thus requiring the casting to have excellent metallurgical quality, high comprehensive mechanical properties, and dimensional accuracy, making casting very difficult.

[0003] like Figure 2 As shown, the wall thicknesses of the inner and outer rings and the blades differ significantly. There is a large hot spot at the transition fillet where the inner and outer rings connect to the blades. During solidification, defects such as overheating, porosity, and cracks are easily generated. At the same time, the nozzle ring operates under harsh conditions. Therefore, the casting is required to have excellent metallurgical quality, high comprehensive mechanical properties, and dimensional accuracy, making the casting very difficult.

[0004] like Figure 3 , 4 As shown, the existing nozzle ring investment casting process involves adding a full-circle process allowance (5) to the inner and outer rings of the nozzle ring to compensate for the hot spot at the blade transition fillet. This method, to a certain extent, compensates for the hot spot at the blade transition fillet, allowing the blade shape and the inner and outer rings to solidify sequentially. The added allowance is then removed by lathe during subsequent machining. However, because the inner and outer rings become thicker after adding the full-circle allowance, they create a more severe thickness unevenness with the blade, generating significant casting stress during solidification and making cracks at the blade root highly likely. During casting, the thickened inner and outer rings generate more heat, hindering heat radiation diffusion and easily leading to overheating of the mold shell, increasing the risk of slag inclusions. Furthermore, the increased thickness of the inner and outer rings results in a low process yield and causes the critical working part—the blade—to receive more heat radiation, resulting in poor cooling and porosity. While increasing the amount of compensation allowance significantly, this process greatly reduces the product's process yield and pass rate, wasting considerable costs in mass production. Summary of the Invention

[0005] The main objective of this invention is to provide a nozzle ring wax mold assembly process that can effectively solve the problems in the background art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a process for preparing a nozzle ring wax mold, comprising the following steps:

[0007] 1) Wax model structure design: Calculate the size and position of the heat-bonding circle at the transition R between the blade and the outer ring in the 3D model of the nozzle ring casting. Design the size and longitudinal cross-sectional profile of the auxiliary block on the outer ring along the outer ring cross-sectional profile at the corresponding heat-bonding point using the rolling method. Determine the transverse width of the auxiliary block based on the diameter of the heat-bonding circle. Design the 3D model of the auxiliary block on the outer ring. Design the 3D model of the auxiliary ring on the inner ring using the rolling method. Divide the nozzle ring into several unit segments according to the number of blades on the nozzle ring. In each unit segment, the blades connect the inner ring segment and the outer ring segment.

[0008] 2) Mold design: Based on the 3D model of the subsidy block and the 3D model of the subsidy ring, design the metal molds for the subsidy block and the subsidy ring, and design the metal molds for the unit segments based on the unit segment structure;

[0009] 3) Pressing wax molds: Using the metal molds from step 2), press wax molds for the patch blocks, patch rings, and unit segments respectively;

[0010] 4) Wax mold assembly: The wax molds of the pressed unit segments in step 3) are glued together in sequence to form the whole wax mold of the nozzle ring. Then, the wax molds of the auxiliary blocks are glued to the outer ring wax mold in sequence according to the heat distribution at the connection between the blade and the outer ring using a limiting fixture. Finally, the auxiliary ring is glued to the inner ring wax mold to obtain the nozzle ring wax mold.

[0011] 5) Wax trimming: The assembled nozzle ring wax mold is trimmed with a wax trimming knife and then integrated with the pouring system.

[0012] Preferably, the limiting fixture includes an inner positioning baffle, an upper positioning baffle, a side positioning block, an upper positioning block, and a support. One end of the inner positioning baffle is connected to the upper positioning baffle, and the other end of the upper positioning baffle is connected to the upper positioning block and the support. The side positioning block is connected to the support via an adjusting bolt, the adjusting bolt is threaded to the support, and the adjusting bolt is movably connected to the side positioning block.

[0013] Preferably, the inner positioning baffle is provided with an exhaust side transition R clearance groove.

[0014] Preferably, the side of the inner positioning baffle near the outer ring is an arc surface, and the diameter of the arc surface is the same as the diameter of the outer ring.

[0015] Preferably, there are two adjusting bolts, which are respectively connected to the upper and lower ends of the side positioning block, and the side of the support is provided with a scale along the axial direction of the adjusting bolt.

[0016] Preferably, the assembly method of the subsidy block is as follows: First, determine the distance d from the positioning side end face of the subsidy block to the exhaust edge of the blade and the tilt angle α of the side of the subsidy block in the 3D model. Adjust the adjusting bolt, adjust the side positioning block to the position of the measured value through the scale and adjust the tilt angle. Make the inner positioning baffle close to the inner surface of the outer ring and the exhaust edge of the blade, and the upper positioning baffle close to the upper surface of the outer ring. Then, attach the upper end face of the subsidy block to the lower end face of the upper positioning block, and attach the side of the subsidy block to the side of the side positioning block, so as to accurately position the subsidy block. Use adhesive wax to fix the subsidy block to the outer ring. Repeat the above steps until all the subsidy blocks are fixed to the outer ring.

[0017] Compared with traditional technologies, the beneficial effects of this invention are as follows: The nozzle ring wax mold prepared by this invention has an independent auxiliary block set at the hot joint R where the outer ring and blades transition. The auxiliary block is calculated laterally using the diameter of the hot joint circle of the hot joint, which avoids excessive shrinkage difference of the overall casting, reduces casting stress, lowers the risk of cracking, controls dimensional deformation, improves the casting qualification rate of the nozzle ring, greatly improves the process yield, increases production efficiency, and saves production costs. In addition, the auxiliary block is positioned by a limiting tooling, which can accurately position the auxiliary block at the hot joint. The operation is simple and the auxiliary block can be welded quickly. While ensuring metallurgical quality, it reduces process allowance and improves the efficiency of industrial mass production. It is suitable for the hot joint treatment of most complex, thin-walled ring castings. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of an existing nozzle ring structure;

[0019] Figure 2 This is a schematic diagram of an existing nozzle annular heat exchanger.

[0020] Figure 3 A schematic diagram of the thermal compensation structure of an existing nozzle ring;

[0021] Figure 4 for Figure 3 A cross-sectional schematic diagram;

[0022] Figure 5 This is a schematic diagram showing the longitudinal dimensions of the subsidy block of the present invention;

[0023] Figure 6 This is a schematic diagram showing the lateral dimensions of the subsidy block according to the present invention;

[0024] Figure 7 This is a schematic diagram of the auxiliary block structure of the nozzle ring wax mold of the present invention;

[0025] Figure 8 This is a schematic diagram of the unit segment structure of the nozzle ring wax mold of the present invention;

[0026] Figure 9 This is a three-dimensional schematic diagram of the nozzle ring wax mold structure of the present invention;

[0027] Figure 10 for Figure 9 A plan view;

[0028] Figure 11 for Figure 10 Schematic diagram of the AA section;

[0029] Figure 12 This is a schematic diagram of the limiting tooling structure of the present invention;

[0030] Figure 13 This is a schematic diagram illustrating the use of the limiting tooling of the present invention. Figure 1 ;

[0031] Figure 14 This is a schematic diagram illustrating the use of the limiting tooling of the present invention. Figure 2 .

[0032] In the diagram: 1. Inner ring; 2. Outer ring; 3. Blade; 4. Hot spot; 5. Process patch for the entire ring; 6. Patch block; 7. Patch ring; 8. Limiting fixture; 81. Inner positioning baffle; 82. Upper positioning baffle; 83. Side positioning block; 84. Upper positioning block; 85. Support; 86. Adjusting bolt; 87. R-shaped clearance groove; 88. Scale. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. All directional indicators (such as up, down, left, right, front, back, etc.) in the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indicator will also change accordingly.

[0034] This embodiment provides a process for preparing a nozzle ring wax mold, including the following steps:

[0035] 1) Wax model structure design: such as Figure 5-6 As shown, the size and position of the heat-bonding circle at the junction R between the blade 3 and the outer ring 2 are calculated in the 3D model of the nozzle ring casting. At the corresponding heat-bonding point 4, the size and longitudinal cross-sectional profile of the auxiliary block 6 on the outer ring 2 are designed using the rolling method along the cross-sectional contour of the outer ring 2. The transverse width of the auxiliary block 6 is determined based on the diameter of the heat-bonding circle, and a 3D model of the auxiliary block 6 on the outer ring 2 is designed, as shown below. Figure 7As shown; the 3D model of the inner ring 1 and the auxiliary ring 7 is designed using the rolling method. Based on the number of blades 3 on the nozzle ring, the nozzle ring is divided into several unit segments, such as... Figure 8 As shown, adjacent unit segments are divided by arc-shaped surfaces to facilitate positioning and fitting. In each unit segment, blade 3 connects inner ring segment 1 and outer ring segment 2.

[0036] 2) Mold design: Based on the 3D model of the subsidy block 6 and the 3D model of the subsidy ring 7, design the metal molds for the subsidy block 6 and the subsidy ring 7, and design the metal molds for the unit segments according to the unit segment structure.

[0037] 3) Pressing wax molds: Using the metal molds from step 2), press wax molds for the patch block 6, patch ring 7, and unit segments respectively;

[0038] 4) Wax model assembly: such as Figure 9-11 As shown, the wax molds of the pressed unit segments in step 3) are glued together in sequence to form the overall wax mold of the nozzle ring. Then, the wax molds of the auxiliary block 6 are glued to the outer ring 2 wax mold in sequence according to the distribution of the heat joint 4 at the connection between the blade 3 and the outer ring 2 through the limiting tool 8. Finally, the auxiliary ring 7 is glued to the inner ring 1 wax mold to obtain the nozzle ring wax mold.

[0039] 5) Wax trimming: The assembled nozzle ring wax mold is trimmed with a wax trimming knife and then assembled with the casting system. The assembly of the casting system and the nozzle ring wax mold is combined with the design of the structure of the auxiliary ring 7 and the auxiliary block 6 before the assembly process is carried out.

[0040] Specifically, such as Figure 12 As shown, the limiting fixture 8 includes an inner positioning baffle 81, an upper positioning baffle 82, a side positioning block 83, an upper positioning block 84, and a support 85. The inner positioning baffle 81 is connected to one end of the upper positioning baffle 82, and the other end of the upper positioning baffle 82 is connected to the upper positioning block 84 and the support 85. The side positioning block 83 is connected to the support 85 via an adjusting bolt 86. The adjusting bolt 86 is threadedly connected to the support 85 and movably connected to the side positioning block 83. The inner positioning baffle 81 is provided with an exhaust side transition R clearance groove 87. The inner positioning baffle 81 has an arc surface on the side near the outer ring 2, and the diameter of the arc surface is the same as the diameter of the outer ring 2. There are two adjusting bolts 86, which are respectively connected to the upper and lower ends of the side positioning block 83. By setting two adjusting bolts 86, the distance and tilt angle of the side positioning block 83 can be adjusted to match the draft angle of the side of the auxiliary block 6. The side of the support 85 is provided with a scale 88 along the axial direction of the adjusting bolts 86. The distance of the side positioning block 83 can be accurately adjusted by using the scale 88, which facilitates the precise adjustment of the position of the auxiliary block 6.

[0041] like Figure 13 , 14As shown, the assembly method of the subsidy block 6 is as follows: First, determine the distance d from the positioning side end face of the subsidy block 6 to the exhaust edge of the blade 3 and the tilt angle α of the side of the subsidy block 6 in the 3D model. Adjust the adjusting bolt 86, adjust the side positioning block 83 to the measured position and adjust the tilt angle through the scale 88, and align the inner positioning baffle 81 with the inner surface of the outer ring 2 and the exhaust edge of the blade 3. Align the upper positioning baffle 82 with the upper surface of the outer ring 2. Then, align the upper end face of the subsidy block 6 with the lower end face of the upper positioning block 84, and align the side of the subsidy block 6 with the side of the side positioning block 83. This limits the radial, height and circumferential directions of the subsidy block 6, thereby accurately positioning the position of the subsidy block 6. Use adhesive wax to fix the subsidy block 6 to the outer ring 2. Repeat the above steps until all the subsidy blocks 6 are fixed to the outer ring 2.

[0042] The prepared nozzle ring wax mold has an independent auxiliary block 6 at the transition R hot spot 4 between the outer ring 2 and the blade 3. The auxiliary block 6 is calculated with the diameter of the hot junction circle of the hot spot 4 in the transverse direction, which avoids excessive shrinkage difference of the overall casting, reduces casting stress, reduces the risk of cracking, controls dimensional deformation, improves the casting qualification rate of the nozzle ring, greatly improves the process yield, improves production efficiency, and saves production costs. In addition, the auxiliary block 6 is positioned by the limiting tool 8, which can accurately position the auxiliary block 6 at the hot spot 4. The operation is simple and the auxiliary block 6 can be welded quickly. While ensuring metallurgical quality, it reduces process allowance and improves the efficiency of industrial mass production. It is suitable for the hot spot 4 part of most complex, thin-walled ring castings, such as most nozzle rings, casings, turbine disks, etc.

[0043] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A process for preparing a nozzle ring wax mold, characterized in that: Includes the following steps: 1) Wax model structure design: Calculate the size and position of the heat-bonding circle at the transition R between the blade and the outer ring in the 3D model of the nozzle ring casting. Design the size and longitudinal cross-sectional profile of the auxiliary block on the outer ring along the outer ring cross-sectional profile at the corresponding heat-bonding point using the rolling method. Determine the transverse width of the auxiliary block based on the diameter of the heat-bonding circle. Design the 3D model of the auxiliary block on the outer ring. Design the 3D model of the auxiliary ring on the inner ring using the rolling method. Divide the nozzle ring into several unit segments according to the number of blades on the nozzle ring. In each unit segment, the blades connect the inner ring segment and the outer ring segment. 2) Mold design: Based on the 3D model of the subsidy block and the 3D model of the subsidy ring, design the metal molds for the subsidy block and the subsidy ring, and design the metal molds for the unit segments based on the unit segment structure; 3) Pressing wax molds: Using the metal molds from step 2), press wax molds for the patch blocks, patch rings, and unit segments respectively; 4) Wax Model Assembly: The wax models of the pressed unit segments in step 3) are glued together in sequence to form the overall wax model of the nozzle ring. Then, the wax models of the auxiliary blocks are glued to the outer ring wax model in sequence according to the heat distribution at the connection between the blade and the outer ring using a limiting fixture. Finally, the auxiliary ring is glued to the inner ring wax model to obtain the nozzle ring wax model. The limiting fixture includes an inner positioning baffle, an upper positioning baffle, a side positioning block, an upper positioning block, and a support. One end of the inner positioning baffle is connected to the upper positioning baffle, and the other end of the upper positioning baffle is connected to the upper positioning block and the support. The side positioning block is connected to the support through an adjusting bolt. The adjusting bolt is threaded to the support and movably connected to the side positioning block. The inner positioning baffle is provided with an exhaust side transition R clearance groove. 5) Wax trimming: The assembled nozzle ring wax mold is trimmed with a wax trimming knife and then integrated with the pouring system.

2. The preparation process of a nozzle ring wax mold according to claim 1, characterized in that: The inner positioning baffle has an arc surface on the side near the outer ring, and the diameter of the arc surface is the same as the diameter of the outer ring.

3. The manufacturing process of a nozzle ring wax mold according to claim 1, characterized in that: There are two adjusting bolts, which are respectively connected to the upper and lower ends of the side positioning block, and the side of the support is provided with a scale along the axial direction of the adjusting bolt.

4. The manufacturing process of a nozzle ring wax mold according to claim 1, characterized in that: The assembly method of the subsidy block is as follows: First, determine the distance d from the positioning side end face of the subsidy block to the exhaust edge of the blade and the tilt angle α of the side of the subsidy block in the 3D model. Adjust the adjusting bolts to adjust the side positioning block to the position of the measured value and adjust the tilt angle. Align the inner positioning baffle with the inner surface of the outer ring and the exhaust edge of the blade, and align the upper positioning baffle with the upper surface of the outer ring. Then, align the upper end face of the subsidy block with the lower end face of the upper positioning block, and align the side of the subsidy block with the side of the side positioning block to accurately position the subsidy block. Use adhesive wax to fix the subsidy block to the outer ring. Repeat the above steps until all the subsidy blocks are fixed to the outer ring.

Images