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Process for strengthening assembly hole through cold extrusion of slotted bushing

A technology of slotted bushing and assembling holes, which is applied in the field of hole cold extrusion strengthening precision machining, can solve the problem of large reaming amount, uneven surface residual stress field of hole wall of workpiece with holes, and increase the cost of hole cold extrusion strengthening technology And other issues

Active Publication Date: 2021-04-16
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Aiming at the hole cold extrusion slotted bush strengthening technology, a large ridge is generated at the liner slot during the hole cold extrusion strengthening process, which causes a large amount of reaming, resulting in a large loss of residual stress, and makes the hole wall of the workpiece with holes not formed properly. The uniform residual stress field on the surface cannot meet the performance requirements of the assembled hole structural parts; after using the slotted bushing for hole cold extrusion strengthening, the slotted bush will be deformed greatly and cannot be reused. Add the hole cold extrusion strengthening technology cost problem

Method used

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  • Process for strengthening assembly hole through cold extrusion of slotted bushing
  • Process for strengthening assembly hole through cold extrusion of slotted bushing
  • Process for strengthening assembly hole through cold extrusion of slotted bushing

Examples

Experimental program
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Effect test

Embodiment 1

[0029] figure 1 It is a process flow diagram of strengthening the assembly hole by cold extrusion of the slotted bush; figure 2 It is a schematic diagram of a strengthened state of a slotted bush cold extruded strengthened assembly hole of the present invention.

[0030] (1) The slotted bush 4 passes through one end of the extruded mandrel 5 and places it on the guide section 6, and is fixed to the fixture through the thread 8 at the tail. Extrusion mandrel 5 and slit bushing 4 pass through auxiliary plate 3 and workpiece 2 with holes. The auxiliary plate 3 is placed in front of the workpiece 2 with holes, and the holes of the auxiliary plate and the assembly holes of the workpiece with holes have the same diameter and are coaxial.

[0031] (2) When the extruding mandrel 5 is pulled out of the assembly hole of the workpiece 2 with holes at a constant speed, the working ring 1 of the extruding mandrel squeezes the slotted bushing 4, and a plurality of slits are opened on the...

Embodiment 2

[0036] Using the ABAQUS finite element simulation analysis software, the assembly hole of the TC4 titanium alloy plate with a diameter of 60 mm × 60 mm × 10 mm and a central hole diameter of 12.12 mm is used to cool the hole with a extrusion amount of 5% using a single-slit bushing and a 4-slit bushing. Simulation of extrusion strengthening process.

[0037] After the assembly hole of the titanium alloy workpiece with holes is cold extruded and strengthened, the wall of the assembly hole produces residual stress in three directions: radial, tangential, and along the thickness of the plate. The residual stress in the three directions of the hole wall has the greatest influence on the performance of the workpiece with holes is the tangential residual stress. Therefore, in Example 2, only the changes of the distance from the hole wall and the tangential residual stress at different positions of the assembled hole wall of the titanium alloy workpiece with holes after the hole cold...

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Abstract

The invention provides a process for strengthening an assembly hole through cold extrusion of a slotted bushing. The process comprises the following steps: (1) the slotted bushing (4) penetrates through one end of an extrusion core rod (5) to be arranged on a guide section (6) and is fixed on a clamp through a thread (8) at the tail part, and the extrusion core rod (5) and the slotted bushing (4) penetrate through a workpiece (2) with a hole to finish installation; (2) when the extrusion core rod (5) is pulled out of the assembly hole of the workpiece with the hole at a constant speed, a working ring of the extrusion core rod extrudes the slotted bushing, the slotted lining elastically expands under the action of extrusion force to extrude the hole wall of the assembly hole of the workpiece with the hole, and the hole wall of the assembly hole is plastically deformed, so that the strengthening effect is achieved; and one or more slots are symmetrically formed in the slotted bushing. The structure is simple, the slotted bushing can be repeatedly used, and therefore the cost of the hole extrusion strengthening process is reduced. A uniform residual stress field is formed on the wall of the assembly hole of the workpiece with the hole, and the fatigue life of the workpiece with the hole is prolonged.

Description

technical field [0001] The invention proposes a reusable multi-slit bush hole cold extrusion strengthening process, which belongs to the technical field of hole cold extrusion strengthening precision machining, and in particular relates to the cold extrusion process of the assembly hole of a workpiece with holes by using a reusable multi-slit bush. Extrusion strengthening. [0002] technical background [0003] Aluminum alloy and titanium alloy are aviation materials with light weight, high strength and excellent mechanical properties, and are widely used in aviation parts. For the assembly holes of typical structures of wide-body airliners, fasteners need to be installed in the assembly holes for assembly. Stress concentration is formed at the edge of the assembly hole, which is prone to cracks, thereby reducing the fatigue performance of the structure and reducing the service life of the structure. Therefore, it is extremely important to increase the fatigue performance a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22F1/00C22F1/18B21C23/00
Inventor 苏宏华刘飞姜廷宇梁勇楠丁文锋徐九华傅玉灿陈燕杨长勇张全利赵正彩殷景飞
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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