Method and device for strengthening inner wall of middle-small diameter long tube through laser shot blasting

Abstract

The invention relates to a method and device for strengthening inner wall of a middle-small diameter long tube through laser shot blasting. The method is characterized by comprising the steps of coating a reflecting film on the surface of a 90-degree taper reflector, reflecting a round laser beam into an annular shape through the taper reflector, and pasting a layer of flexible coated film on the inner wall of an enhanced tube to be strengthened. The central line of the laser beam, the central axis of the tube and the central axis of the 90-degree taper reflector are on the same line and parallel to a guide rail. The annular laser reflected by the reflector vertically irradiates the flexible coating film on the inner wall to produce plasma shock wave acting on the inner wall of the tube so as to form a residual compressive stress layer on the inner wall of the tube, so that the rigidity, corrosion resistance, wearability, fatigue strength and other performances of the inner wall of the tube are improved. The taper reflector moves from one end to the other end of the tube to realize a continuous strengthening process of the whole tube wall. The method and the device disclosed by the invention not only can be applied to tubes with middle-small diameters in a certain range, and continuous laser shot blasting can be realized for tubes with relatively longer length.

Description

technical field [0001] The invention relates to the field of laser processing, in particular to a technology for strengthening the inner wall of a pipe fitting, specifically a method and device for strengthening the inner wall of a medium-small-diameter long pipe by laser shot peening. Background technique [0002] In petroleum, chemical industry, natural gas, nuclear energy and other industries, pipe fittings are widely used. However, during the long-term use of pipe fittings, due to the corrosion of the external environment and the internal fluid medium, impurity wear, high pressure, etc., it will inevitably produce certain damage. Damage to rupture will cause serious consequences to production and safety. For example, the high-pressure fuel pipe of the diesel engine ruptures or leaks to the hot surface of the turbocharger due to high-pressure pulse load and high-frequency vibration, causing a fire at the machine; the steam pressure of the boiler pipe of the power station ...

AI Technical Summary

Problems solved by technology

However, there are still deficiencies in this method: ①Due to the limitation of the size of the spray gun, it can only be applied to pipes with a diameter greater than 25 mm; ②The size of the spray gun support must match the inner diameter of the pipe. Replace accordingly; ③When the length of the pipe is too long, the feed movement of the pipe is blocked due to the soft material, resulting in uneven shot peening

However, there are still deficiencies in this device: ①The surface hardened layer after laser quenching is not uniform, and the surface quality is not high; ②The size of the robot device needs to be adjusted according to the inner diameter of the tube; ③The roller may be stuck by the inner wall during the crawling process of the robot device

Although the above method satisfies the laser shot peening of small-diameter holes, it also has some shortcomings: ①For long pipes, the absorbing layer and the constraining layer on the reflective cone need to be repeatedly coated due to consumption, and continuous shot peening cannot be achieved; ② The size of the energy absorbing rod needs to be changed according to the size of the hole; ③ Due to the consumption of a large amount of plasma explosion waves on the reflection cone, the force and strengthening effect on the inner wall of the hole are reduced

In summary, if the laser shot peening of the inner wall of the medium and small diameter long tubes is realized, the performance of the tubes will be greatly improved, but there are still certain defects in the known related invention patents

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