scholarly journals Cold Forging Effect on the Microstructure of Motorbike Shock Absorbers Fabricated by Tube Forming in a Closed Die

2021 ◽  
Vol 11 (5) ◽  
pp. 2142
Author(s):  
Trung-Kien Le ◽  
Tuan-Anh Bui
Keyword(s):  
Material Flow ◽  
Cold Forging ◽  
Technological Parameters ◽  
Forming Process ◽  
Tube Forming ◽  
Shock Absorbers ◽  
Thin Walled Tube ◽  
Thin Walled ◽  
Quality Of Products ◽  
Forming Defects

Motorbike shock absorbers made with a closed die employ a tube-forming process that is more sensitive than that of a solid billet, because the tube is usually too thin-walled to conserve material. During tube forming, defects such as folding and cracking occur due to unstable tube forming and abnormal material flow. It is therefore essential to understand the relationship between the appearance of defects and the number of forming steps to optimize technological parameters. Based on both finite element method (FEM) simulations and microstructural observations, we demonstrate the important role of the number and methodology of the forming steps on the material flow, defects, and metal fiber anisotropy of motorbike shock absorbers formed from a thin-walled tube. We find limits of the thickness and height ratios of the tube that must be held in order to avoid defects. Our study provides an important guide to workpiece and processing design that can improve the forming quality of products using tube forming.

Law of Metal Flow of Thin-Walled Conical Part With Variable Section During Spinning

2020 ◽  
Author(s):  
Shu Xuedao ◽  
Xia Yingxiang ◽  
Zhu Ying ◽  
Li Zixuan ◽  
Ye Bohai
Keyword(s):  
Metal Flow ◽  
Conical Part ◽  
Forming Process ◽  
Finite Element Software ◽  
Axial Tensile ◽  
Variable Section ◽  
Spinning Process ◽  
Thin Walled ◽  
Forming Defects

Abstract During the spinning process of the variable-section thin-walled conical parts, the metal flow law is relatively complicated and the flange is prone to be unstable, which resulting in wrinkling and other defects. In this paper, the variable-section conical part of superalloy GH1140 is taken as the research object. The spinning forming process is numerically simulated by using Simufact Finite Element software and the metal flow in each stage of the forming process is analyzed. The flow velocity shows an annular distribution as a whole. The metal near the center of the circle flows more slowly, and the metal far from the circular flange flows more quickly. In the direction of thickness, the velocity of metal flow decreases gradually. Under the feeding action of the roller, the metal in front of the roller is subjected to axial tensile stress, tangential and radial compressive stress, resulting in a strain state of one-way tension and two-way compression. The metal moves along the negative direction of the rotary wheel feed, resulting in the increase of the sheet wall thickness. The correctness of the model in this paper is further verified by spinning experiments. The research results provide a theoretical basis for analyzing the mechanism of forming defects and improving the quality of spinning forming of conical thin-walled parts with variable sections.

scholarly journals Sheet Bulk Forming of Thin-Walled Components with External Gearing through Upsetting Using Controllable Deformation Zone Method

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Xincun Zhuang ◽  
Meile Liang ◽  
Shengfa Zhu ◽  
Yin Zhu ◽  
Zhen Zhao
Keyword(s):  
Material Flow ◽  
Deformation Zone ◽  
Effective Strain ◽  
Sheet Forming ◽  
Forming Process ◽  
Zone Method ◽  
Forming Mechanism ◽  
Bulk Forming ◽  
Thin Walled ◽  
Controllable Deformation

AbstractSheet-bulk metal forming (SBMF) is a promising process for manufacturing complex sheet components with functional elements. In this study, the entire forming process for a typical thin-walled component with external gearing is investigated, including sheet forming and bulk forming processes. Deep drawn cups are prepared during sheet forming; subsequently, upsetting is performed on the sidewall to form external gearing. The upsetting method performed is known as upsetting with a controllable deformation zone (U-CDZ). Compared with the conventional upsetting method, a floating counter punch with a counter force is used in the U-CDZ method such that the forming mechanism is changed into the accumulation of the deformation zone instead of deformation throughout the entire sidewall. The effects of the counter force and material flow are investigated to understand the mechanism. The forming quality, i.e., the formfilling and effective strain distribution, improved, whereas a high forming load is avoided. In addition, a punch with a lock bead is used to prevent folding at the inner corner during the experiment.

scholarly journals Effect of floating axial holder on oscillating cold forging of spline shaft

2018 ◽  
Vol 249 ◽  
pp. 02001
Author(s):  
N Y Ben ◽  
Q Zhang ◽  
M G Lee
Keyword(s):  
Material Flow ◽  
Elastic Recovery ◽  
Nonlinear Function ◽  
Material Model ◽  
Cold Forging ◽  
Fe Model ◽  
Tooth Shape ◽  
Constitutive Material Model ◽  
Spline Shaft ◽  
Forming Defects

Oscillating technique is applied into the axial forging process of spline shaft to decrease the forming load and improve the quality of products. A floating axial holder with dwell force is designed to control the material flow. The influences of the floating axial holder have been analysed by finite element (FE) simulation and then verified by experiments. A FE model that considers material property change, elastic recovery and elastoplastic friction was built. The constitutive material model, which is mainly composed of variable elastic modulus and rate-dependent hardening, was used to simulate changes in material properties. Results showed that material flow was improved by decreasing dwell force. Tooth shape can be controlled by changing the dwell force of floating axial holder. The nonlinear function between addendum circle diameter and dwell force has been found. Hence, an optimal value of dwell force was determined considering the forming force, forming defects and tooth shape. Based on the simulating results, the optimal and irrational parameters of dwell force and frequency have been compared in the experiments. The typical defects of flash and accumulation can be eliminated by using the floating axial holder with optimal parameters.

Towards the characterization of fracture in thin-walled tube forming

2016 ◽  
Vol 119 ◽  
pp. 12-22 ◽  
Author(s):  
Gabriel Centeno ◽  
Maria Beatriz Silva ◽  
Luis M. Alves ◽  
Carpóforo Vallellano ◽  
Paulo A.F. Martins
Keyword(s):  
Tube Forming ◽  
Thin Walled Tube ◽  
Thin Walled

A New Stress Mathematical Model of Deformation Zone while Straightening Thin-Walled Tube

2013 ◽  
Vol 652-654 ◽  
pp. 1488-1493
Author(s):  
Zi Qian Zhang ◽  
Yun Hui Yan ◽  
Hui Lin Yang
Keyword(s):  
Mathematical Model ◽  
Theoretical Model ◽  
Plastic Zone ◽  
Deformation Zone ◽  
Shell Theory ◽  
Theoretical Calculations ◽  
Technological Parameters ◽  
Membrane Shell ◽  
Thin Walled Tube ◽  
Thin Walled

As there was no precise theoretical model for predicting the stress of deformation zone while straightening thin-walled tube, some technological parameters depended mostly on the experience of workers and on the results of trials, therefore by means of the membrane shell theory the equilibrium differential equations of stress is obtained firstly, then we analyze the strain of deformation zone, finally lead to a new theoretical model for predicting the stress in the elastic and plastic zone. Subsequently the simulated experiments have been done, the results show that the theoretical calculations coincide well with the simulated results, the errors are within 1％of the calculations, it is testified that the model is correct and efficient for the thin-walled tube straightening.

Investigation on wrinkling behaviors of metal thin-walled tube in pulsating hydroforming with axial feeding

2020 ◽  
pp. 030932472094906
Author(s):  
Guolin Hu ◽  
Chunrong Pan ◽  
Zheng Liu
Keyword(s):  
Tube Hydroforming ◽  
Great Influence ◽  
Forming Process ◽  
Axial Feeding ◽  
Tube Wall Thickness ◽  
Forming Parameters ◽  
Thin Walled Tube ◽  
Thin Walled ◽  
The Relationship ◽  
Tube Bulging

Pulsating tube hydroforming with axial feeding is an effective method to improve the forming performance of thin-walled tube. A beneficial wrinkle can make the tube wall thickness more uniform and create a greater bulging height during forming process. The method of expressing the degree of wrinkle with geometrical and mechanical criteria is applied to distinguish the wrinkle types, and thus, the wrinkles can be divided into beneficial ones and harmful ones based on the deformation wrinkle features with different forming parameters. The wrinkling behavior in tube pulsating hydroforming with axial feeding was investigated in this article by experimental study, numerical simulation and theoretical analysis. The results showed that loading parameters had great influence on formability and wrinkling behaviors and that the beneficial wrinkles could be identified and used effectively by controlling the relation of wrinkling degree and forming parameters. Furthermore, the evolution processes of wrinkling behaviors in tube-bulging experiment were observed, the characteristics of wrinkling in every stage were analyzed and the relationship between wrinkling degree and forming parameters was established in the experiment.

scholarly journals Research on AZ80 + 0.4%Ce (wt %) Ultra-Thin-Walled Tubes of Magnesium Alloys: The Forming Process, Microstructure Evolution and Mechanical Properties

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 563 ◽  
Author(s):  
Zhaoming Yan ◽  
Min Fang ◽  
Zhendong Lian ◽  
Zhimin Zhang ◽  
Jiaxuan Zhu ◽  
...  
Keyword(s):  
Magnesium Alloys ◽  
Wall Thickness ◽  
Vickers Hardness ◽  
Hardness Test ◽  
Optical Microscope ◽  
Forming Process ◽  
Average Grain Size ◽  
Thin Walled Tube ◽  
Thin Walled ◽  
Variable Wall

Ultra-thin-walled tubes of magnesium alloys have received more and more attention in producing precision components for medical devices. Therefore, thin-walled tubes with high quality are desperately needed. In this study, the process of multi-pass variable wall thickness extrusion was carried out on an AZ80 + 0.4%Ce Mg alloy with up to five passes—one-pass backward extrusion and four-pass extension—to fabricate the seamless thin-walled tube with an inside diameter of 6.0 mm and a wall thickness of 0.6 mm. The average grain size decreased from 46.3 μm to 8.9 μm at the appropriate deformation temperature of 350 °C with the punch speed of 0.1 mm/s. X-ray diffraction (XRD), optical microscope (OM), scanning electron microscopy (SEM), and the Vickers hardness (HV) tester were utilized to study the phases, microstructure, and hardness evolution. It can be observed that low deformation temperatures (240 °C and 270 °C) and low strain (1 pass extrusion and 1 pass extension) lead to twins that occupy the grains to coordinate deformation, and a slip system was activated with the accumulation of strain. The results of the Vickers hardness test showed that twinning, precipitation of second phases, twinning dynamic recrystallization (TDRX), and work hardening were combined to change the hardness of tubes at 240 °C and 270 °C. The hardness reached 93 HV after the third pass extension without annealing at 350 °C.

A New Bionic Elastic Mandrel for Application in the Spatial Consecutive RDB with no Straight Line

2015 ◽  
Vol 25 ◽  
pp. 12-18 ◽  
Author(s):  
Lan Fang Jiang ◽  
Wei Ming Lin ◽  
Dong Hui Wen ◽  
Hong Liu ◽  
Cong Da Lu ◽  
...  
Keyword(s):  
Structural Characteristics ◽  
Internal Surface ◽  
Forming Process ◽  
Straight Line ◽  
Space Saving ◽  
Thin Walled Tube ◽  
Bending Radius ◽  
Continuous Support ◽  
Thin Walled ◽  
Draw Bending

Thin-walled spatial bending tube can not only provide engineering design with higher flexibility and lighter structure, but also enhance the construction of space saving and aerodynamics improvement. Based on rotary draw bending technique, a new method for spatial consecutive bending with no straight line for thin-walled tube was put forward. Firstly, a new bionic elastic mandrel was developed by analyzing the structural characteristics of the squilla. It mainly consisted of bowl-shaped mandrel balls, an elastomer and a mandrel shank. The bowl-shaped mandrel balls, nested matching one another, generated a non-smooth surface which can provide continuous support for internal surface of the tube wall. It could also achieve small bending radius. The elastomer featured of certain bending stiffness and enough tensile strength. Secondly, a curved clamping die was advanced to clamp the spatial consecutive bending tube with no straight line effectively. Based on the shape of the bending tube after the former bending forming process, the curved clamping dies which can match the shape of the former bending tube were designed for the later bending. Lastly, bending experiments was performed. A thin-walled tube made of Q235 with two passes, one bending angle 90° and the other 180° was taken for example and the spatial consecutive bending tube with no straight line was successfully obtained. It is of significant importance in enriching the spatial bending tube technique and achieving the small bending radius.

scholarly journals Numerical Analysis of the Forming Process of Head Toothing in Rolling Extrusion on a Shaft from Aluminum Alloy 7075 / Analiza Numeryczna Kształtowania Uzębienia Czołowego W Procesie Przepychania Obrotowego Na Wałku Ze Stopu Aluminium 7075

2015 ◽  
Vol 60 (4) ◽  
pp. 2739-2742 ◽  
Author(s):  
J. Bartnicki ◽  
J. Tomczak
Keyword(s):  
Aluminum Alloy ◽  
Numerical Analysis ◽  
Material Flow ◽  
Numerical Models ◽  
Numerical Calculations ◽  
Technological Parameters ◽  
Forming Process ◽  
Real Material ◽  
Aluminum Alloy 7075 ◽  
Extrusion Technology

This paper presents the forming method of head toothing with the application of rolling extrusion technology. Tools numerical models were used in numerical calculations. The presented numerical results concern metals flow kinematics, distributions of stresses and strains. Determined in the process technological parameters of head toothing forming allow foreseeing real material flow in the experiment planned for conducting.

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