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Fundametal Research on Cold Extrusion Process of Internal Threads in High Strength Steel Q460

Author: ShaXiaoWei
Tutor: LiXiangFeng；ZuoDunWen
School: Nanjing University of Aeronautics and Astronautics
Course: Mechanical Manufacturing and Automation
Keywords: High Strength Steel Internal thread Cold extrusion Finite Element Extrusion torque Extrusion temperature
CLC: TG376
Type: Master's thesis
Year: 2010
Downloads: 74
Quote: 1
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Abstract

Currently, for the landing gear with the internally threaded member , with the internal threads of the cutting method of manufacturing lead to the undercarriage of the fatigue life of only one - third of the life of the overall aircraft . Therefore, the use of state-of-the-art anti - fatigue manufacturing process to improve the internal thread fatigue strength , so that the landing gear to achieve the same level of life to the airframe , it is particularly important . In this paper, carried out by the Q460 high strength steel thread cold extrusion manufacturing process of anti-fatigue , the main work and the results obtained are as follows : 1. Internally threaded Cold extrusion forming mechanism for analysis , the results showed that : internal thread cold extrusion using extrusion taps edge tooth the repeated extrusion workpiece metal , to produce a plastic deformation process . After extrusion the inner threaded surface of tissue fibrosis and distributed along the tooth - shaped thread root surface there is a certain degree of hardening layer , so that the extrusion internally threaded a tensile strength and fatigue resistance are improved. Uniaxial tensile test study carried out on the Q460 high strength steel , the stress-strain curve of the material , to lay the foundation for the subsequent finite element simulation ; material and get a range of performance parameters , such as : yield strength of 810MPa tensile strength of 925MPa, elongation of 18.56% , the section shrinkage rate was 47.3% . 3 Based on ANSYS numerical simulation of thread -shaped area of ??the cold extrusion , the stress , strain the law . The results show that : the cold extrusion within the thread root and flank are subject to axial and radial compressive stress , will play an important role in the presence of compressive stress on the root and flank strengthen ; dactylon parts maximum axial compressive stress is 525MPa, the maximum value of the radial compressive stress 550MPa; flank parts of the maximum axial compressive stress of 725MPa the radial stress maximum to 360MPa ; farther from the root flank , the smaller the value of compressive stress . Internal thread cold extrusion process research carried out Q460 high strength steel results show that: piece bottom diameter of the workpiece rotational speed and the cooling and lubricating fluid type on the the extrusion torque generated in the cold extrusion process and the extrusion temperature . reasonable piece bottom diameter , workpiece speed and cooling lubrication can be that piece bottom diameter of 21.24mm ~ 21.26mm the workpiece speed in 20r/min ~ 32r/min to reduce extrusion torque and squeezed temperature ; between the cooling and lubricating fluid is polydimethylsiloxane (PDMS) , the higher the quality of the cold extrusion of the internal thread .

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Metal pressure processing > Extrusion > Extrusion process
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