A tension-torsion coupled cold extrusion strengthening mandrel and its strengthening method for holes

Abstract

The invention discloses a pull-twisting coupled cold extrusion strengthening mandrel and a strengthening method thereof, which comprise a mandrel body; the mandrel body includes a mandrel strengthening head, a middle part of a mandrel and a mandrel tail; , Both ends of the back are tapered surfaces, the outer contour of the middle part of the mandrel strengthening head is a cylindrical surface, and the central angles at the same interval on the cylindrical surface are cut along the length direction of the mandrel to cut off the fan-shaped cylindrical surface corresponding to the central angle; the middle part of the mandrel is a cylinder Shaped, rectangular grooves are set on the cylindrical surface; threads are set on the tail of the mandrel, and are threadedly connected with the stretching device. The present invention cuts off the fan-shaped cylindrical surface corresponding to the central angle along the length direction of the mandrel with the same central angle, reduces the contact area between the mandrel and the hole wall by 50% during the strengthening process, and reduces the theoretical strengthening resistance in the stretching direction by 50%. It reduces the difficulty of the cold extrusion process with high strengthening amount and large diameter hole, and effectively solves the problem of inability to strengthen due to high strengthening amount and large diameter hole structure strengthening resistance.

Description

technical field [0001] The invention belongs to the technical field of mechanical processing, and in particular relates to a tension-twisting coupled cold extrusion strengthening mandrel of a hole and a strengthening method thereof. Background technique [0002] Mechanical connection is widely used in the aerospace field due to its advantages of simple process, good reliability, easy disassembly, and large load capacity. For example, in aircraft assembly and manufacturing, it accounts for more than 70% of aircraft connection structures. Although the mechanical connection has many advantages, the mechanical connection hole destroys the integrity of the overall structure and causes adverse effects such as stress concentration and local damage. At the same time, it causes complex stress distribution around the hole under external load, which is a typical structural danger point. Especially under cyclic loading, studies have shown that in flight fatigue accidents, more than 70% ...

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Problems solved by technology

[0005] The purpose of the present invention is to address the above-mentioned deficiencies in the prior art, to provide a tension-twist coupled cold extrusion strengthening mandrel and its strengthening method to solve the problems of high strengthening amount and large-diameter hole structure that cannot be strengthened due to large strengthening resistance. The problem

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