Special-shaped hole machining method and special-shaped hole

Abstract

The invention discloses a special-shaped hole machining method and a special-shaped hole and relates to the technical field of laser machining. According to the method, femtosecond or picosecond or nanosecond pulse laser is adopted, and a mode completely based on scanning galvanometer filling machining is provided. The method comprises the steps that firstly, a through hole smaller than the hole diameter requirement is machined so that gasification objects and fusion objects formed in the machining process can be discharged and re-coagulation objects are prevented from depositing; then, roughmachining of a special-shaped hole diffusion section is conducted; then, the laser focusing position is adjusted, broaching is conducted on the basis of a dust discharge through hole, and a cylindrical through hole meeting the hole diameter requirement is machined; and finally, the focus position is precisely adjusted, and the diffusion section is machined layer by layer. By means of the special-shaped hole machining method and the special-shaped hole, heat-induced defects such as recasting layers, microcracks, coating collapse and the like generated in the process that in the prior art, a special-shaped hole is machined, and in particular, the special-shaped hole is machined in a workpiece with the surface coated with a thermal barrier coating are avoided; and in addition, the shape and dimension precision of the special-shaped hole are improved.

Description

technical field [0001] The invention relates to the technical field of laser machining holes, in particular to a method for machining a special-shaped hole and the special-shaped hole. Background technique [0002] Special-shaped holes have long been used in the cooling structure of aero-engine turbine blades due to their better film cooling effect. [0003] The special-shaped hole is mainly composed of a through hole and a diffusion section. According to the structural characteristics of the special-shaped hole, various processing methods have been adopted at home and abroad. The earliest method adopted is electric discharge machining, but the efficiency is low; in order to improve efficiency, two-step processing is adopted, that is, laser processing of cylindrical holes, and electric discharge forming electrode processing of the diffusion section of the hole; there are also millisecond pulse laser direct cutting processing. Method, the processing of the diffusion section ...

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Problems solved by technology

[0005] The efficiency of complete electric discharge machining is low, and thermally induced defects such as recasting layers will occur, and it is impossible to complete the hole making on parts whose surface is first prepared with a non-conductive ceramic-based thermal barrier coating;

[0006] The process and equipment of laser-EDM secondary processing are complicated, and the accuracy of secondary alignment is not easy to guarantee;

[0007] Although the millisecond pulse laser cutting method has high efficiency, the processing shape is limited. It is necessary to ensure that the cutting process along the surface of the hole wall of the diffusion section does not destroy the shape integrity of the special-shaped hole. It is necessary to strictly control the cutting depth or take protective measures such as filling protective materials, and Millisecond long-pulse laser cutting with large energy will cause severe thermal effects, resulting in thermally induced defects such as recast layers and microcracks

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