Method for additive manufacturing through depositing, forming, impacting, forging and compositing through double laser beams

Abstract

The invention discloses a method for additive manufacturing through depositing, forming, impacting, forging and compositing through double laser beams. The method comprises the following technical characteristics that (1) the two laser beams with different functions simultaneously and mutually cooperate to stack materials in a depositing area layer by layer to form workpieces; and (2) a first continuous laser deposits metal powder through the heat effect, at the same time, a second short pulse laser directly acts on the deposited metal surface within the forging temperature range, and the second short pulse laser impacts and forges deposited layers within the forging temperature range through the impact wave mechanical effect. The method is characterized in that the double laser beams fully utilize the heat effect and the impact wave mechanical effect and simultaneously conduct coupling work at the same time, so that crystal particles of each deposited layer are refined, the strength and plasticity of the whole block body materials and the uniformity of the crystal particle size are improved, internal defects such as air holes and heat stress of the deposited layers are eliminated, the internal quality and machinery mechanical comprehensive performance of metal parts are improved remarkably, and macroscopic deformation and cracking problems are effectively controlled.

Description

technical field [0001] The invention relates to the technical field of additive manufacturing, in particular to a dual laser beam welding forming impact forging composite additive manufacturing method. Background technique [0002] Additive manufacturing is different from traditional "removal" manufacturing. It does not require original embryos and molds. It can directly generate objects of any shape by adding materials based on computer graphics data. It is an important development direction of advanced manufacturing technology. [0003] The existing pure laser cladding 3D forming process is essentially a "free additive forming" process, which generally has the following common technical problems: (1) Internal defects: process parameters, external environment, fluctuations and changes in the melt state of the molten pool, scanning The transformation of the filling track, etc., may produce various special internal metallurgical defects in the local area of ​​the part, such a...

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Problems solved by technology

[0003] The existing pure laser cladding 3D forming process is essentially a "free additive forming" process, which generally has the following common technical problems: (1) Internal defects: process parameters, external environment, fluctuations and changes in the melt state of the molten pool, scanning The transformation of the filling track, etc., may produce various special internal metallurgical defects in the local area of ​​the part, such as pores, unfused, cracks and shrinkage internal defects, etc.

It has the following problems that affect the practicability: (1) laser shock strengthening after the cladding layer is cooled, its plastic deformation is small, it is difficult to eliminate internal defects such as voids, shrinkage porosity, and microcracks inside the cladding layer; (2) The complexity of the cladding heating device will increase exponentially with the increase in the size and structural complexity of the cladding parts, and it is even difficult to realize, and the local heating technology is even more difficult

It will take a very long time to heat a cooled 3D printed large-scale component to 700°C, and it will be very inefficient to heat up once after several layers are deposited.

(3) It is difficult for mechanical shot peening to achieve shot peening in the area, and it is very difficult to clean the shot peening

In addition, there are the following problems that affect the practicability: (1) After the SLM sintered layer forms a cross-section of the product, the product is impact-strengthened, and the plastic deformation is small, and it is difficult to eliminate the voids, shrinkage porosity, and micro-cracks inside the cladding layer. Internal defects; (2) Laser shock peening is a special term that was first proposed by the United States (Lasershock-processing, Laser peening, Laser shock-peening), and was listed as one of the key manufacturing technologies of the fourth-generation aero-engine by the United States First, the lasers currently used in engineering applications are neodymium glass lasers, YAG lasers and YLF lasers, and the laser pulse power density must exceed 10 9 W / cm 2 , but it is not yet possible to transmit such a high-pulse laser beam with an optical fiber; (3) The shock wave intensity decays with a negative exponential law inside the general metal material, and the attenuation is faster in the sintered layer with defects such as void shrinkage and porosity, and the propagation law is more Complicated, it is difficult to detect effective signals with PVDF pressure sensors. With the increase of sintered parts, the detection of laser shock wave signals becomes more and more difficult, and even the authenticity of the signals cannot be judged.

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