Effects of Local Heating on Material Flow in Free Forming Process

2006 ◽  
Author(s):  
O. Okman ◽  
M. O¨zmen ◽  
H. Huwiler ◽  
A. E. Tekkaya
Keyword(s):  
Induction Heating ◽  
Material Flow ◽  
Failure Modes ◽  
Local Heating ◽  
Mechanical Analysis ◽  
Local Deformation ◽  
Forming Process ◽  
Manufacturing Method ◽  
Laser Beam Scanning ◽  
Electromagnetic Calculations

A novel manufacturing method is investigated, in which a proper temperature gradient is created within workpiece in order to control local material flow during free forming. The main motivation is to produce complicated shapes by reducing the flow stress on the regions, where local deformation is desired to take place. A sufficient control of temperature within the material results in the required product shape even in the absence of complicated dies. Besides the lower tooling costs the process provides, the heat energy applied to the workpiece is less than that in conventional hot forming processes, which is currently a strong alternative for manufacturing of such products. In the study, heating is realized by means of induction heating and laser beam scanning. The process is investigated experimentally on circular cylinder specimens made of different materials, namely Ti6Al4V, X5CrNi18/9 and 16MnCr5. The effect of process parameters on the mode of deformation is analyzed by finite element method (FEM). The thermo-mechanical analysis of induction heating is supported by electromagnetic calculations. The two alternative heating methods are compared. Affects of heating on multiple locations is investigated for induction heating applications. A brief overview of the process is presented and conclusions are drawn on the effectiveness, limitations, failure modes and applicability of the process.

An Electromagnetic and Thermo-Mechanical Analysis of High Frequency Induction Heating for Steel Plate Bending

2006 ◽  
Vol 326-328 ◽  
pp. 1283-1286 ◽  
Author(s):  
Jang Hyun Lee ◽  
Kyung Ho Lee ◽  
Jong Sung Yun
Keyword(s):  
Electromagnetic Field ◽  
Induction Heating ◽  
Eddy Currents ◽  
Steel Plate ◽  
Local Heating ◽  
Mechanical Analysis ◽  
Plate Bending ◽  
Heating Equipment ◽  
Process Comparison ◽  
Thermal Mechanical Analysis

Eddy currents of electromagnetic field leads not only to the local heating of plate but also to the thermal-elasto-plastic deformation in the induction heating. It is necessary to have a simulation model to attract the possibility of induction heating equipment and to study the deformation behavior. The goal of present paper is to investigate the possibility of induction heating equipment for steel plate bending. The residual stress distribution of induction heating is investigated by an electromagnetic analysis in conjunction with thermal-mechanical analysis. A computational model based on FEA is used to study the electromagnetic field and thermalmechanical process. Comparison with the residual strain fields and deformation of both heating shows that the induction heating has good similarity with the gas heating.

The Analysis of Radial Deformation on Annular Local Heating Processed Pipe. Study of fitted pipe's manufacturing method due to annular local heating process (Report 2).

1995 ◽  
Vol 13 (4) ◽  
pp. 619-627
Author(s):  
Toshiaki Araki ◽  
Hisao Hasegawa ◽  
Takeshi Yamada ◽  
Hiroyuki Matsumura ◽  
Kazuhiro Aoyama ◽  
...  
Keyword(s):  
Local Heating ◽  
Heating Process ◽  
Radial Deformation ◽  
Manufacturing Method

scholarly journals Fracture Mechanical Analysis of Thin-Walled Cylindrical Shells with Cracks

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 592
Author(s):  
Feng Yue ◽  
Ziyan Wu
Keyword(s):  
Fracture Mechanics ◽  
Tensile Stress ◽  
Failure Modes ◽  
Cylindrical Shells ◽  
Crack Tip ◽  
Mechanical Analysis ◽  
J Integral ◽  
Thin Walled Structures ◽  
Circumferential Tensile Stress ◽  
Thin Walled

The fracture mechanical behaviour of thin-walled structures with cracks is highly significant for structural strength design, safety and reliability analysis, and defect evaluation. In this study, the effects of various factors on the fracture parameters, crack initiation angles and plastic zones of thin-walled cylindrical shells with cracks are investigated. First, based on the J-integral and displacement extrapolation methods, the stress intensity factors of thin-walled cylindrical shells with circumferential cracks and compound cracks are studied using linear elastic fracture mechanics, respectively. Second, based on the theory of maximum circumferential tensile stress of compound cracks, the number of singular elements at a crack tip is varied to determine the node of the element corresponding to the maximum circumferential tensile stress, and the initiation angle for a compound crack is predicted. Third, based on the J-integral theory, the size of the plastic zone and J-integral of a thin-walled cylindrical shell with a circumferential crack are analysed, using elastic-plastic fracture mechanics. The results show that the stress in front of a crack tip does not increase after reaching the yield strength and enters the stage of plastic development, and the predicted initiation angle of an oblique crack mainly depends on its original inclination angle. The conclusions have theoretical and engineering significance for the selection of the fracture criteria and determination of the failure modes of thin-walled structures with cracks.

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.

scholarly journals Material flow control in sheet-bulk metal forming processes using blasted tool surfaces

2018 ◽  
Vol 190 ◽  
pp. 13003 ◽  
Author(s):  
Marion Merklein ◽  
Maria Löffler ◽  
Daniel Gröbel ◽  
Johannes Henneberg
Keyword(s):  
Metal Forming ◽  
Material Flow ◽  
Simultaneous Occurrence ◽  
Tribological Behaviour ◽  
Forming Process ◽  
Functional Elements ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Main Challenge ◽  
Functional Components

Highly-integrated and closely-tolerated functional components can be produced by sheet-bulk metal forming which is the application of bulk forming operations on sheet metals. These processes are characterized by a successive and/or simultaneous occurrence of different load conditions such as stress and strain states which reduce the geometrical accuracy of the functional elements. Thus, one main challenge within sheet-bulk metal forming is the identification of methods to control the material flow and thus to improve the product quality. One suitable approach is to control the material flow by local modifications of the tribological conditions. Within this study requirements regarding the needed adaption of the tribological conditions for a specific sheet-bulk metal forming process were defined by numerical investigations. The results reveal that a local increase of the friction leads to an improved die filling of the functional elements. Based on these results abrasive blasting as a method to modify the tool surface and thus influencing the tribological behaviour was investigated. For the determination of the tribological mechanism of blasted tool surfaces, the influence of different blasting media as well as blasting pressures on the surface integrity and the friction were determined. The correlations between surface properties and friction conditions were used to derive the mechanisms of blasted tool surfaces.

Hybrid forming process of AA 6108 T4 thin sheets: Modelling by neural network solutions

2008 ◽  
Vol 223 (5) ◽  
pp. 535-545 ◽  
Author(s):  
M Barletta ◽  
A Gisario ◽  
S Guarino
Keyword(s):  
Neural Network ◽  
Local Heating ◽  
Elastic Strain Energy ◽  
Laser Source ◽  
Training Algorithms ◽  
Thin Sheets ◽  
Forming Process ◽  
Neural Network Models ◽  
Linear Deformation ◽  
Source Power

The highly non-linear deformation processes occurring in most dynamic sheet metal forming operations cause large amounts of elastic strain energy to be stored in the formed material and massive related springback phenomena. Therefore, this paper investigates how effective a laser source is in reducing the extent of springback in mechanical contact forming operations. The hybrid forming process investigated was composed of using a high-power diode laser to induce local heating of mechanically bent AA 6108 T4 thin sheets in order to minimize the extent of the springback. In particular, experiments were carried out to assess the influence of the leading process parameters such as laser source power, scan speed, and starting elastic deformation of the mechanically bent sheets. It was found that the trends in the experimental response of residual deflection were always consistent with the operating parameters. Artificial intelligence techniques were then used to model the hybrid forming process. The extent of the springback in the hybrid forming process of AA 6108 T4 thin sheets was predicted by using different neural network models and training algorithms. Lastly, the reliability of the best neural network solutions was checked by comparing these solutions with experimental results and by developing an ad hoc first approximation technical model.

scholarly journals High productivity micro rotary swaging

2018 ◽  
Vol 190 ◽  
pp. 15002 ◽  
Author(s):  
Eric Moumi ◽  
Marius Herrmann ◽  
Christian Schenck ◽  
Bernd Kuhfuss
Keyword(s):  
Material Flow ◽  
Process Variations ◽  
Main Process ◽  
Forming Process ◽  
Workpiece Material ◽  
High Productivity ◽  
Rotary Swaging ◽  
Micro Parts ◽  
Intensive Investigation ◽  
Clamping Device

Rotary swaging is an incremental forming process with two main process variations plunge and infeed rotary swaging. With plunge rotary swaging, the diameter is reduced within a limited section whereas the infeed rotary swaging enables a diameter reduction over the entire workpiece length. The process is now subject to intensive investigation for manufacturing of micro parts. By increasing the process speed, failures occur particularly due to inappropriate material flow. In plunge rotary swaging, the workpiece material can flow radially into the gap between the dies and thus the workpiece quality suffers. In infeed rotary swaging the workpiece material flows against the feeding direction and can provoke bending or braking of the workpiece. Therefore, additional measures to control both the radial and the axial material flow to enable high productivity micro rotary swaging are investigated. The radial material flow during plunge rotary swaging can be controlled by elastic intermediate elements that enable an increase of productivity by factor three. A spring-loaded clamping device that enables an increase of the productivity by factor four can temporarily buffer the axial material flow in infeed rotary swaging against the feeding direction.

scholarly journals Investigation of Slip Occurrence in the Ring Rolling Process

2019 ◽  
Vol 291 ◽  
pp. 02006
Author(s):  
Andrzej Gontarz ◽  
Piotr Surdacki
Keyword(s):  
Wall Thickness ◽  
Failure Modes ◽  
Rolling Process ◽  
Ring Rolling ◽  
Thickness Reduction ◽  
Main Stage ◽  
Forming Process ◽  
Limit Values ◽  
Ring Shape ◽  
Ring Rolling Process

Ring rolling is a hot forming process for producing rings that have large diameters when compared to their cross sections. This process is very dynamic and involves considerable variations in ring shape and size. One of the failure modes in ring rolling processes is slip that occurs when a thickness reduction, exceeds the limit value. The thickness reduction depends on the tool speed and dimensions as well as ring size, and varies over time. This paper reports results of a study investigating the thickness reduction with respect to slip occurrence. In terms of wall thickness reduction, the process can be divided into three distinct stages (excluding the sizing stage): (i) initial stage corresponding to the first revolution of the roll, (ii) main stage, when the proper ring rolling takes place, (iii) final stage, when the main roll does not move in an axial direction but the ring is being formed during one revolution of the tool. It has been found that the most slip-prone moment is the end of the second and the beginning of the third stage of the ring rolling process, when the wall thickness reduction is the highest. Based on a comparison of the calculated thickness reduction and its limit values, it could be predicted whether slip would occur, and if so – in what stage of the rolling process. Numerical results and experimental findings are in good agreement.

Improved Sheet Bulk Metal Forming Processes by Local Adjustment of Tribological Properties

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
H. Hetzner ◽  
J. Koch ◽  
S. Tremmel ◽  
S. Wartzack ◽  
M. Merklein
Keyword(s):  
Contact Pressure ◽  
Metal Forming ◽  
Material Flow ◽  
System Analysis ◽  
Sheet Thickness ◽  
Fe Model ◽  
Forming Process ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Functional Features

This paper is focused on a combined deep drawing and extrusion process dedicated to the new process class of sheet bulk metal forming (SBMF). Exemplified by the forming of gearings, combined sheet and bulk forming operations are applied to sheet metal in order to form local functional features through an intended and controlled change of the sheet thickness. For investigations on the form filling and the identification of significant influencing factors on the material flow, a FE simulation model has been built. The FE model is validated by the results of manufacturing experiments using DC04 with a thickness of 2.0 mm as blank material. Due to the fact that the workpiece is in extensive contact to the tool surface and that the pressure reaches locally up to 2500 MPa, the tribological conditions are a determining factor of the process. Thus, their influence is discussed in detail in this paper. In the first instance, different frictional zones having a distinct effect on the resulting material flow are identified and their effect on improved form filling is demonstrated. Subsequently, a more comprehensive methodology is developed to define tribological zones of forming tools. For this, a system analysis of the digital mock-up of the forming process is performed. Besides friction, other relevant aspects of forming tool tribology like contact pressure, sliding velocity, and surface magnification are considered. The gathered information is employed to partition the tools into tribological zones. This is done by systematically intersecting and re-merging zones identified for each of the criterion. The so-called load-scanning test allows the investigation of the friction coefficient in dependence of the contact pressure and possible loading limits of tribological pairings. It provides an appropriate tribological model test to evaluate tribological measures like coatings, surface textures and lubricants with respect to their targeted application in particular zones. The obtained results can be employed in the layout of further forming processes to reach the desired process behavior. This can be, for example, an improved form filling, less abrasive wear and adhesive damage or lower forming forces, respectively tool load for an improved durability of the die.

Development of Manufacturing Method for Truss Core Panel Based on Origami-Forming

2015 ◽  
Author(s):  
Hoan Thai Tat Nguyen ◽  
Phuong Thao Thai ◽  
Bo Yu ◽  
Ichiro Hagiwara
Keyword(s):  
Forming Process ◽  
Robot System ◽  
Cutting Method ◽  
Manufacturing Method ◽  
Truss Core ◽  
Equivalent Bending Stiffness ◽  
Lightweight Structure ◽  
Partition Method ◽  
In Fire ◽  
Honeycomb Panel

Although honeycomb panel is widely used in various stages, its adhesive for gluing honeycomb core and plate may burn by fire, leading to the requirement of another lightweight and high stiffness panel. Recently, an Origami structure called Truss Core Panel (TCP) is known as a lightweight structure that has equivalent bending stiffness as honeycomb panel, and safer in fire. However, some difficulties are found in forming TCP in general. In this study, a new forming process of TCP based on origami-forming is developed. In particular, the TCP is partitioned into several parts that are flat unfoldable into 2D crease patterns. After that, blanks of material are cut as the shapes of those crease pattern, and be formed by a robot system to get the desired 3D shape. Firstly, partition method by dividing TCP into pyramid cores and sheet plate is presented, suggesting an ability to manufacture a wider range of structure than before. Tools arrangement of robot device and a countermeasure for springback are considered. Next, by applying Origami unfolding technique, an improvement of partition method is proposed: dividing TCP into cores rows, and then searching for a Origami crease pattern in order to fold that cores row. The cutting method of every core is modified for reducing the number of facets, making the problem simpler. Finally, an Origami crease pattern based on this new cutting method is presented, producing cores row with any number of cores.

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