Selective laser melting forming and post-treatment method for thin-wall interlayer cooling structure

Abstract

The invention relates to the technical field of additive manufacturing, and discloses a selective laser melting forming and post-treatment method for a thin-wall interlayer cooling structure. The method comprises the following steps that (1) a three-dimensional model is optimized and established based on the design of an additive manufacturing technology; (2) the established model is placed as required; (3) a local part is cut out to carry out forming and post-treatment testing, and iterative optimization is carried out on the model according to a liquid flow result; (4) supports are added; (5) selective laser melting forming is carried out; (6) powder is cleaned away, and wax filling protection is carried out; (7) the external support is removed by adopting methods of wire cut electricaldischarge machining, machining, manual polishing and the like, and then dewaxing treatment is carried out after the above operation is finished; and (8) heat treatment is carried out, finishing is carried out on the inner surface of a thin-wall interlayer through chemical polishing, and the smoothness of an inner cavity meets the requirement.

Description

technical field [0001] The invention relates to the technical field of additive manufacturing, in particular to a thin-wall interlayer cooling structure laser selective melting forming and post-processing method. Background technique [0002] The thin-wall interlayer cooling structure is the main structural form to effectively ensure the normal service of the rocket engine thrust chamber in the high temperature and high pressure environment, and is mainly used in the combustion chamber, contraction and expansion section and expansion section. The combustion chamber is the place where the propellant is mixed and burned, where the fuel and the oxidant are fully mixed and burned to generate high-temperature gas. The contraction and expansion section is a key part of the thrust chamber. It is a double bell-shaped structure. One end is connected to the combustion chamber, and the other end is connected to the expansion section. Its main function is to convert the heat energy of t...

AI Technical Summary

Problems solved by technology

The traditional manufacturing process cannot directly form the interlayer cooling structure as a whole, and it is manufactured by brazing the inner and outer walls

There are following problems in above-mentioned processing technology: the first, performance stability is poor

The interlayer cooling body of the thrust chamber adopts the brazing process of the inner and outer walls, and the problem of blockage or bulge of the cooling channel often occurs due to the uneven flow of the brazing material, which affects the performance of the product

In addition, the body adopts a segmented welding process after brazing. Due to the deformation of each segment after brazing, the butt joint accuracy of each segment is poor and the quality of the weld seam is poor, which reduces the quality and stability of the engine.

Second, the pass rate is low

When assembling the inner and outer walls of the interlayer cooling assembly in the thrust chamber, the inner wall needs to be bulged to fit the inner and outer walls together. However, due to material rebound, the brazing gap between the inner and outer walls of the small end after bulging is relatively large, resulting in poor brazing quality. During the hydraulic test assessment, there will be problems such as pressure bulging in the weaker brazing seam area, resulting in the scrapping of the product

Third, the processing cycle is long

Since the interlayer cooling component of the force chamber cannot be integrally formed by the traditional process, it needs to be divided into multi-section structures. Each section is brazed separately and then welded into an overall structure. The structure and process are complicated. The forming process involves forging, heat treatment, machining, More than a dozen processes such as bulging, brazing, and electron beam welding lead to a long production cycle. The entire production cycle takes nearly 4 months, which is not conducive to the rapid development of the engine

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