CN-122007340-A - Method for manufacturing shell of narrow groove of large turbine working blade

CN122007340ACN 122007340 ACN122007340 ACN 122007340ACN-122007340-A

Abstract

The invention discloses a method for manufacturing a shell of a narrow groove of a large turbine working blade, which relates to the technical field of methods for manufacturing shells of the narrow groove of the large turbine working blade; the method comprises the steps of precisely assembling to form a module, carrying out strict dimension inspection on the manufactured ceramic core and main wax mould, assembling the ceramic core and the wax mould to form a module ‌, forming a shell, dip-coating, sanding and drying the module according to a standard investment casting shell forming process, carrying out post-treatment, roasting and dewaxing the dried module to form a formed shell, and checking whether the dewaxed formed shell meets the standard. According to the scheme, the restriction of a limited space similar to a narrow groove structure in the investment casting industry is eliminated through the ceramic core structure, the problem of restricting the shell quality is radically solved, and the effective positioning of the free end of the ceramic core and the structural stability of the module in the shell manufacturing process are realized through the design of the positioning interface, the shell anchoring and the reserved gap.

Inventors

ZHENG YONGSHUAI
DU HONGQIANG
Tong Zhanwu
HAN LEI
LIU CHUANG

Assignees

辽宁汉文动力科技有限责任公司

Dates

Publication Date: 20260512
Application Date: 20260304

Claims (5)

1. A method for manufacturing a shell of a narrow groove of a large turbine working blade is characterized by comprising the following steps: S100, structural analysis and ceramic core design; S110, analyzing a three-dimensional model of the casting to identify a limited space, wherein the limited space comprises all areas with depth-to-width ratios larger than a set threshold, narrow grooves or deep cavities which are difficult to uniformly cover by paint and difficult to fill by sand; s120, designing the ceramic core, wherein the ceramic core comprises a design filling body, a positioning interface and a shell anchoring; S121, the filling body is a ceramic core which is in negative shape matching with the shape of the limited space, the ceramic core can be assembled with the wax mould of the blade main body to fill the limited space, and a reserved gap between the ceramic core and the wax mould is arranged on the filling body; s122, the positioning interface is arranged on a contact surface of the ceramic core adjacent to the wax pattern of the blade main body; s123, anchoring the shell on the outer surface of the ceramic core exposed in the shell; S200, precisely assembling to form a module, carrying out strict dimension inspection on the manufactured ceramic core and the main body wax mould, assembling the ceramic core and the wax mould to form a module ‌, ensuring the position of the free end of the main body ceramic core to be accurate, sealing the joint seam of the ceramic core and the wax mould by using wax or special sealant, and preventing paint from penetrating into a reserved gap during shell manufacturing; S300, manufacturing a shell, namely dip-coating, sanding and drying the module according to a standard investment casting shell manufacturing process; and S400, post-processing, namely roasting and dewaxing the dried module to prepare a molded shell, checking whether the dewaxed molded shell meets the standard, and enabling the molded shell meeting the standard to enter a casting link.
2. A method for manufacturing a shell for a narrow groove of a large turbine rotor blade according to claim 1, wherein the shell is formed by annular grooves, grid-shaped pits or roughened texture areas.
3. The method for manufacturing a narrow groove shell of a large turbine rotor blade according to claim 1, wherein the positioning interface is a groove arranged on a solid part of the ceramic core.
4. The method for manufacturing the shell of the narrow groove of the large turbine working blade according to claim 1, wherein the post-treatment further comprises a judging step of judging whether the abnormal shell of the internal structure is detected, if so, the shell can be repaired and polished to eliminate the abnormal shell, if so, the shell enters a casting step, and if not, the shell can be destroyed, and sand and ceramic cores are recovered.
5. A method for manufacturing a narrow slot shell of a large turbine rotor blade according to claim 1, wherein the reserved gap on one side is the sum of thermal expansion, assembly tolerance compensation and process safety margin, the thermal expansion (mm) is assumed to be DeltaL, the relevant length (mm) of the component at room temperature is assumed to be L 0 , the thermal expansion coefficient (/ DEGC) of the material is alpha, the temperature change (DEGC) is DeltaT, and the calculation formula of the thermal expansion (mm) DeltaL is DeltaL=L 0 ×alpha×DeltaT.

Description

Method for manufacturing shell of narrow groove of large turbine working blade Technical Field The invention relates to the technical field of a shell manufacturing method for a narrow groove of a large turbine working blade, in particular to a shell manufacturing method for a narrow groove of a large turbine working blade. Background In investment casting, the shell making of narrow deep groove structures (high aspect ratio) is a serious challenge, with the core difficulty that uniform penetration coverage of the coating, effective removal of air bubbles, dense packing of sand particles, and uniform drainage of moisture are difficult to achieve in confined spaces. Coating defects are easily formed because the coating is difficult to completely wet the bottom and the side wall of the tank due to high viscosity and surface tension, and bubbles are retained due to unsmooth exhaust paths to form a cavity weak point. During sanding, sand grains are difficult to penetrate into the bottom of the groove, and bridging is easy to accumulate at the inlet, so that the local strength is insufficient. During the drying process, the evaporation of solvent/water in the tank is blocked, which is far slower than that in the external area, and the severe shrinkage stress is initiated, so that the coating is extremely easy to crack or peel. During dewaxing, the molten wax expands under heat, but the discharge passage is narrow, and the internal pressure tends to crack the insufficiently reinforced shell. . According to the traditional shell making process, means of optimizing materials, process parameters and the like are mostly adopted. For example, a low-viscosity high-wettability coating is selected, superfine sand is adopted and assisted by fluidized sand spraying or vibration to promote permeation and filling, and vibration and direction adjustment are combined to drive bubbles during dip coating. The exhaust and drying control are enhanced, the temperature and humidity of the drying environment are accurately regulated and controlled, the directional air flow is enhanced, and process exhaust holes are additionally arranged if necessary. Strictly dewaxing management, namely adopting a slow heating and prolonged heat preservation strategy to reduce internal pressure. The comprehensive application of the means is a common measure for ensuring the structural shell integrity, but the use effect is unstable, and more shell defects still occur. For example, in the prior art, patent number 202011069730.9, although ceramic cores are used as filling bodies to solve the problem of difficulty in manufacturing the shell in a limited space, stability of connection and positioning accuracy between the ceramic cores and the shell are not considered, expansion amounts of different materials when heated are different, and if no relative solving means is adopted, the percent of pass of the shell is not much higher than that of the traditional shell manufacturing process. Disclosure of Invention In order to solve the above problems, that is, the problems set forth in the background art, the present invention provides a method for manufacturing a shell of a narrow groove of a large turbine rotor blade, comprising the following steps: S100, structural analysis and ceramic core design; S110, analyzing a three-dimensional model of the casting to identify a limited space, wherein the limited space comprises all areas with depth-to-width ratios larger than a set threshold, narrow grooves or deep cavities which are difficult to uniformly cover by paint and difficult to fill by sand; s120, designing the ceramic core, wherein the ceramic core comprises a design filling body, a positioning interface and a shell anchoring; S121, the filling body is a ceramic core which is in negative shape matching with the shape of the limited space, the ceramic core can be assembled with the wax mould of the blade main body to fill the limited space, and a reserved gap between the ceramic core and the wax mould is arranged on the filling body; s122, the positioning interface is arranged on a contact surface of the ceramic core adjacent to the wax pattern of the blade main body; s123, anchoring the shell on the outer surface of the ceramic core exposed in the shell; S200, precisely assembling to form a module, carrying out strict dimension inspection on the manufactured ceramic core and the main body wax mould, assembling the ceramic core and the wax mould to form a module ‌, ensuring the position of the free end of the main body ceramic core to be accurate, sealing the joint seam of the ceramic core and the wax mould by using wax or special sealant, and preventing paint from penetrating into a reserved gap during shell manufacturing; S300, manufacturing a shell, namely dip-coating, sanding and drying the module according to a standard investment casting shell manufacturing process; and S400, post-processing, namely roasting and dewaxing the dried module to prepare