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Method of welding steam turbine nozzle by electron beam

An electron beam welding and steam turbine technology, applied in electron beam welding equipment, welding equipment, other manufacturing equipment/tools, etc., can solve the problems of high processing accuracy of steam throat, poor efficiency, steam leakage from nozzles, etc. The appearance and shape are beautiful, the efficiency is improved, and the welding quality is improved.

Active Publication Date: 2008-12-17
HARBIN TURBINE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] In order to solve the problem that the existing nozzle groups of 300MW and 600MW steam turbines have always used EDM to machine the guide vane steam channel profile, and adopt bolts to tighten the structure, this structure has nozzle steam leakage, affects efficiency, long cycle, and high processing of steam channel throat The accuracy is poor, and the tolerance can only reach ±1mm. A method of using electron beam welding for steam turbine nozzles is provided. The specific technical solution to solve the above problems is as follows:

Method used

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Examples

Experimental program
Comparison scheme
Effect test

specific Embodiment approach 1

[0011] Specific embodiment one: the steam turbine nozzle welding step of the present embodiment is as follows:

[0012] Step 1. Using the casting process, two half-ring nozzle chambers are cast. The nozzle chamber radius is 475mm, the outer ring radius is 630mm, the material is 1Cr9MoVNbN or improved 9Cr%, and the surface finish of the ring is Ra=3.2μm. The generation of magnetism does not require grinding machine processing;

[0013] Step 2. Clean the surface of the cast nozzle chamber; use mechanical or chemical methods (mechanical such as polishing wheels, scrapers, etc.; chemicals such as acetone, alcohol, etc.) to remove rust, scale, paint, oil, etc. on the surface of the nozzle chamber material. Emulsion and its removal of dust on the surface of the workbench and fixtures;

[0014] Step 3. Fix half of the cleaned nozzle chamber on the workbench, place the baffle, and place the baffle in the cavity of the nozzle chamber to prevent the electron beam from damaging the nozz...

specific Embodiment approach 2

[0019] Specific embodiment two: the accelerating voltage in step four of this embodiment is 45KV, the welding speed is 50mm / min, the welding distance is 150mm, the electron beam current is 150mA, the focusing current is 3.75A, the scanning waveform is square, and the scanning frequency is 100Hz , the welding angle is 10 degrees, the scanning swing Vx is 1 mm, and Vy is 1 mm. After the nozzle welded and formed in step 5 is kept warm for 0.5 hours, it is kept warm at 760 ° C for 7 hours. Other steps are the same as in the first embodiment.

specific Embodiment approach 3

[0020] Specific embodiment three: the accelerating voltage in step four of this embodiment is 55KV, the welding speed is 200mm / min, the welding distance is 220mm, the electron beam current is 260mA, the focusing current is 2.1A, the scanning waveform is circular, and the scanning frequency is 420Hz, welding angle of 90 degrees, scanning swing Vx of 1.8mm, and Vy of 2.0mm, heat the nozzle formed by step five welding for 1 hour, and then heat it at 730°C for 5 hours to obtain the best welding data of the steam turbine nozzle. Other steps are the same as in the first embodiment.

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Abstract

The invention relates to a method for using electron beam to weld ejection of turbine, wherein it comprises: 1, casting ejector room; 2, washing the surface of ejector room; 3, fixing the ejector room in the work bench; 4, using electron welding machine to weld the ejector in vacuum room, while the data should be matched; 5, cooling welded ejector and thermally treating, cooling and welding two semi rings. The invention can welding at single surface and form at two surfaces, without back root cleaning, with high welding quality, high efficiency and reduced producing period.

Description

technical field [0001] The invention relates to a welding method for a steam turbine nozzle. Background technique [0002] The steam turbine nozzle is the first threshold for new steam to enter the cylinder, and the welding quality is high. If there is a problem, it will directly affect the safe operation of the unit. Its material is improved 9% Cr steel with poor weldability. In addition, the structural space of this component is very small, it is very difficult to clean the root after welding, and double-sided welding cannot be performed. However, the existing 300MW and 600MW steam turbine nozzle groups have always used EDM to machine the guide vane steam channel profile, and use bolts to tighten the structure. This structure has nozzle steam leakage, affects efficiency, long cycle time, and poor machining accuracy of steam channel throat. The tolerance can only reach ±1mm, which is far from the design requirement tolerance of ±0.10mm. Contents of the invention [000...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B23K15/06B23K15/00B23P23/00
Inventor 杨浩李金华宫在龙王庆友刘力田杨东波邓伟佳杜绶
Owner HARBIN TURBINE
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