A method and device for underwater laser shock strengthening of prismatic shaped holes

Abstract

The invention relates to laser processing and in particular relates to a prismatic irregular hole underwater laser shock peening method and a device for realizing the same. The method comprises the following steps: precisely matching a matching pin of which the surface hardness value is higher than that of a workpiece with a prismatic irregular hole, putting the workpiece in an underwater opposite hole side area and performing laser shock peening; introducing incident laser beams into the prismatic irregular hole for peening the inner wall of the prismatic irregular hole by utilizing a total reflector arranged in the prismatic irregular hole, adopting large-size square light spot laser beams in a non-prismatic area, adopting small-size square light spot laser beams in gradual transition in a prismatic area, and linearly changing the sizes of the light spots perpendicular to the edge direction in the prismatic area, wherein the sizes of the light spots are smaller at positions closer to the edge. Meanwhile, a jump mode and a thickened absorption layer are matched, the laser shock peening quality is guaranteed. According to the method, hole edge collapse and a plasma shielding effect can be effectively avoided, and the method is suitable for peening the inner wall of the prismatic irregular hole with the edge angle of less than 90 degrees and a hole edge area.

Description

technical field [0001] The invention relates to the field of laser processing, in particular to a method for underwater laser shock strengthening of prismatic special-shaped holes and a device for realizing the method, especially suitable for strengthening the inner wall and edge area of ​​prismatic special-shaped holes with an edge angle less than 90°. Background technique [0002] Special-shaped holes are different from conventional cylindrical holes, and are usually specially designed to meet certain technical requirements. For example, in order to reduce the weight of the aircraft, there are many different-shaped special-shaped holes on the aircraft board; For stress conditions, the piston pin hole is designed in a cylindrical shape with a horn or an ellipse. Compared with a cylindrical hole, the curvature of the profile of the special-shaped hole fluctuates greatly, so the stress concentration on the special-shaped hole is more serious. [0003] Prismatic special-shaped...

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Problems solved by technology

[0005] When laser shock strengthening is performed on the edge area of ​​the prismatic special-shaped hole, it is easy to collapse the edge of the hole; and when laser shock strengthening is performed on the edge area of ​​the prismatic special-shaped hole, since the edge angle is less than 90°, the laser beam will first irradiate the edge area Plasma is generated on the surface of the outer prism special-shaped hole, thereby forming a "plasma shielding" effect, preventing the laser beam from irradiating the angular area, and affecting the effect of laser shock strengthening; To achieve full coverage of the processing area, an overlap rate of more than 30% is usually required, so the laser energy waste in the overlapping area of ​​the spot is relatively large; and the current laser shock strengthening processing method is point-by-point sequential processing, the absorption caused by the previous laser shock The warping of the layer will affect the subsequent laser shock, so that the stress distribution in the strengthened area of ​​the prismatic shaped hole is not uniform

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