Micro-hole strengthening method combining cone pressure and laser impact

Abstract

The invention discloses a micro-hole strengthening method combining cone pressure and laser impact, and belongs to the technical field of surface strengthening of parts, wherein the strengthening method comprises the following steps of: implementing laser impact strengthening on a position to be processed with holes of a plate material / workpiece, pressing the position to be processed with the holes into the plate material / workpiece by a conical pressure head with comparatively high hardness, and processing micro-holes on the plate material / workpiece; or pressing into the position to be processed with the holes of the plate material / workpiece by the conical pressure head with the comparatively high hardness, drawing out the conical pressure head, implementing laser strengthening treatment on the position to be processed with the holes on the back surface / opposite surface and surrounding parts thereof, and punching the plate material / workpiece. According to the method disclosed by the invention, the problem of poor depth of a pressure stress layer or pulling stress generated after processing the position to be processed with the holes of the plate material by single laser impact strengthening, and the problem on micro-hole strengthening of some plate material-type parts which just permit the laser plate material strengthening on single surface are solved at the same time, so that the processed micro-holes have the pressure stresses in a thickness direction.

Description

technical field [0001] The invention belongs to the technical field of surface strengthening of parts, relates to laser shot peening strengthening and pressing treatment on the surface of parts, and provides a small hole strengthening method combining cone pressure and laser shock. Background technique [0002] In mechanical structures in aerospace and other fields, holes play an important role in mechanical connection mechanisms. Generally speaking, holes are often the stress concentration parts of the whole part. Components often start to fail at the hole position, resulting in the scrapping of the entire part. In other words, the lifetime of the entire component is reduced due to the lifetime of the hole itself. Therefore, there is an urgent need for an effective small hole strengthening process, the purpose of which is to improve the mechanical properties of parts with holes, so that they can be safer, more reliable and have a longer fatigue life during use. [0003] ...

AI Technical Summary

Problems solved by technology

However, this strengthening method is limited by the hole size. When the hole size is small to a certain extent, it is impossible or difficult to realize, and the stress distribution in the thickness direction after shot peening is not uniform.

[0004] In Chen Jie's patent CN 102205488A, a method for cold extrusion processing of slotted bushes is described. The principle is to put slotted bushes on a On the tapered extrusion rod with interference, the extrusion mandrel is forcibly passed through the inner hole of the part, and the extrusion force is evenly transmitted to the inner hole wall of the part through the slotted bushing, so that residual compressive stress is generated around the inner hole , but it is very easy to break the rod during the extrusion process. Once the rod is broken, it is extremely difficult to remove the broken mandrel from the part. The slotted bushing is a consumable process bushing. Every time a hole is squeezed, a slotted bushing must be thrown away. The bushing costs more than two hundred dollars per extruded mandrel, and the small-diameter slotted bushing costs $1-2 each. The cost is huge and unbearable, and the production cost is too high and unacceptable

[0005] In the patent CN 101024862A, a method and device for strengthening the hole wall based on laser shock wave technology are described. This patent mainly installs a reflection cone in the existing hole The conical surface is coated with an energy-absorbing layer material, and then laser shock strengthened, and a uniform strengthened layer can be obtained. However, for small holes, especially small holes with a diameter of less than 3mm, the use of this strengthening method is limited, and the strengthening effect is difficult. Guaranteed

[0006] In the patent CN 101126117A, a laser shock treatment method for a hole structure is described. The implementation method is to place a mandrel or a bushing in the hole before laser shock strengthening Inside, the mandrel or bushing is flush with the surface of the treatment hole. After the laser shock strengthening is completed, the mandrel or bushing is removed. The feature of this patent is that the hole is first opened and then strengthened. The mandrel or bushing is added to ensure the position of the hole No deformation after laser shock strengthening to ensure the quality of the hole after strengthening. small holes cause damage

[0007] In the patent CN 102517423A, a small hole strengthening method is described. The implementation method is to use a laser with a large spot and high energy to treat the surface of the metal plate to be opened. Impact strengthening, so that the metal plate produces residual compressive stress deep in the thickness direction, and then uses a laser with a small spot and low energy to perform secondary impact strengthening on the surface of the metal plate around the position where the hole is to be opened, so that the surface of the metal plate produces a relatively strong pressure. Good residual compressive stress, and finally drilling, this method avoids the problem of poor quality of the hole end surface caused by drilling first and then laser shock strengthening, but when the thickness of the plate is large, this method cannot guarantee the hole quality. The entire thickness direction of the wall is compressive stress, it is difficult to obtain the ideal compressive stress effect

[0008] Therefore, it is of far-reaching significance to develop a new small hole strengthening process to ensure that the hole wall is under compressive stress along the thickness direction. In the present invention, laser shock strengthening and The method of mechanical pressing can effectively ensure that the position of the hole to be processed is under compressive stress in the thickness direction, and the compressive stress is relatively uniform. After searching the existing documents at home and abroad, it is found that there is no such method similar to the method of the present invention at home and abroad. research report

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