scholarly journals Influencing the forming zone by altering the contact pressure in a bending process

2021 ◽  
Author(s):  
Peter Frohn-Sörensen ◽  
Jonas Reuter ◽  
Bernd Engel
Keyword(s):  
Contact Pressure ◽  
Flexible Manufacturing ◽  
Material Flow ◽  
Angular Size ◽  
Bending Moment ◽  
Production Environment ◽  
Forming Process ◽  
Bending Process ◽  
Large Product ◽  
Forming Methods

In a modern production environment, flexible manufacturing methods are important because an overall trend towards mass customization and on-demand production is observed. Kinematic and incremental forming methods with generic tools can provide a large product variation but a deeper understanding of the forming mechanisms is required for process modelling, e.g. Incremental Swivel Bending (ISB). Particularly crucial is to identify the influences on the forming zone in order to purposefully control the material flow of a forming process. For a bending process where the bending moment is transmitted by clamping tools, this paper presents a method to alter the contact pressure distribution in order to affect the angular size and strain gradient of the forming zone. In the light of these results, the presented method can be deployed for a tooling with adaptive contact pressure to directly influence material flow, in particular using generic tools to overall provide a better control of flexible forming methods.

Theoretical Investigation of the Bending Process of the Pre-Strained Metal Sheet

2020 ◽  
Vol 299 ◽  
pp. 351-357
Author(s):  
Sergey A. Tipalin ◽  
Michael A. Petrov ◽  
Yuriy A. Morgunov
Keyword(s):  
Thin Sheet ◽  
Bending Moment ◽  
Metal Sheet ◽  
Roll Forming ◽  
Forming Process ◽  
Bending Process ◽  
Punch Radius ◽  
Zero Radius ◽  
Strain Stress ◽  
Roll Forming Process

During the bending operation of the thin sheet materials by the punch with the near-to-zero radius the special technological operation should be carried out. It means that the metal sheet obtained a certain thinning value, which is usually done in the form of the channel-concentrator or groove by pre-drawing operation in a cold state. It follows to the pre-straining and strengthening of the material. The authors investigated the strain hardened sheet's area after roll forming process theoretically, and obtained the strain-stress distribution inside the sheet during the bending operation. It was found out that the increase of the prior deformation during pre-straining in the bend layer follows to the increase of the radial and tangential stresses and displacement of the neutral axis inside the blank during bending operation. As a result, the bending moment changes its values depends on the punch radius and strain hardening.

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.

scholarly journals Research on Four-Point Air Bending Process and Contour Detection Method for JCO Forming Process of LSAW Pipes

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 859
Author(s):  
Zhang ◽  
Wang ◽  
Yu ◽  
Zhao
Keyword(s):  
Detection Method ◽  
Bending Moment ◽  
Experimental System ◽  
Ccd Camera ◽  
Contour Detection ◽  
Segment Length ◽  
Forming Process ◽  
Air Bending ◽  
Bending Process ◽  
Measuring Machine

Aiming at the forming efficiency and roundness of the longitudinal submerged arc welded (LSAW) pipes in JCO (J-shape to C-shape to O-shape) forming process, this paper proposes a four-point air bending process. Compared with the traditional three-point air bending process, The new process can provide a more uniform bending moment, does not need to crimp the edges of steel sheet, shorten the residual straight segment length, and lengthen the forming length in single pass. The mechanical model is established to analyze the static equilibrium conditions and elastic–plastic deformation. The process is simulated by using the software package ABAQUS, to find the maximum punch spacing, and further determine the formulation principles of other process parameters. In addition, a contour detection method for the LSAW pipes in forming process is proposed based on machine vision (planar-array CCD camera produced by Gray Point Corporation, Vancouver, Canada). This method can not only quickly detect the contour of each pass, but also splice the detected contours together to obtain the overall contour with the given splicing algorithm. According to the measured contour, the bending angle, radius, and roundness can be calculated, to correct the punch reduction in the next pass and improve the forming accuracy of the pipes. Finally, an experimental system is designed to verify the proposed four-point bending JCO forming process and contour detection method. The result shows that the error between the contour detection method and CMM (coordinate measuring machine) is less than 0.5% for the overall contour, the two experimental pipes require 13 and 15 passes respectively, the roundness of pipes are less than 1.1%, which is much better than that of traditional three-point bending JCO forming process.

A springback prediction method for double-curved plate bent with the multi-point forming method

2020 ◽  
Vol 234 (12) ◽  
pp. 1939-1952
Author(s):  
Tao Yue ◽  
Chunguo Liu
Keyword(s):  
Prediction Method ◽  
Bending Moment ◽  
Stiffened Panel ◽  
Forming Process ◽  
Manufacturing Method ◽  
Element Simulation ◽  
Blending Method ◽  
Bending Process ◽  
Springback Prediction ◽  
Bent Plate

Stiffened panel as a kind of thin-walled component is widely used in aircraft. A novel stiffened panel manufacturing method has been proposed that the plate is bent into designed shape first with multi-point forming method and then milled into integral panel. However, in the bending process, springback is a great issue. In this paper, an analytical method is proposed to predict the springback of the double-curved bent plate in multi-point forming process. The method takes advantage of the loading force, which is obtained by the stress in the thickness direction, and the arrangement of the punches to calculate the bending moment in the forming process. Through Bezier surface blending method, the profile after springback was constructed. Moreover, the strain and stress variation through thickness during loading and unloading process were also analyzed. And the finite element simulation and bending experiment were conducted to make verification. The results show that the method proposed can effectively predict the springback of the double-curved bent plate in multi-point forming.

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.

Finite Element Modeling of Self-Loosening of Bolted Joints

2004 ◽  
Author(s):  
Ming Zhang ◽  
Yanyao Jiang ◽  
Chu-Hwa Lee
Keyword(s):  
Finite Element ◽  
Contact Pressure ◽  
Bending Moment ◽  
Shear Loading ◽  
Transverse Load ◽  
Fe Model ◽  
Bolted Joint ◽  
Cyclic Bending ◽  
Second Stage ◽  
Cyclic Bending Moment

A three-dimensional finite element (FE) model with the consideration of the helix angle of the threads was developed to simulate the second stage self-loosening of a bolted joint. The second stage self-loosening refers to the graduate reduction in clamping force due to the back-off of the nut. The simulations were conducted for two plates jointed by a bolt and a nut and the joint was subjected to transverse or shear loading. An M12×1.75 bolt was used. The application of the preload was simulated by using an orthogonal temperature expansion method. FE simulations were conducted for several loading conditions with different preloads and relative displacements between the two clamped plates. It was found that due to the application of the cyclic transverse load, micro-slip occurred between the contacting surfaces of the engaged threads of the bolt and the nut. In addition, a cyclic bending moment was introduced on the bolted joint. The cyclic bending moment resulted in an oscillation of the contact pressure on the contacting surfaces of the engaged threads. The micro-slip between the engaged threads and the variation of the contact pressure were identified to be the major mechanisms responsible for the self-loosening of a bolted joint. Simplified finite element models were developed that confirmed the mechanisms discovered. The major self-loosening behavior of a bolted joint can be properly reproduced with the FE model developed. The results obtained agree quantitatively with the experimental observations.

Experimental Assessment of High Temperature Formability of Boron Steel Sheet Manufactured With a Spring Compound Bending Die

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Yang Li ◽  
Yong-Phil Jeon ◽  
Chung-Gil Kang
Keyword(s):  
Mechanical Properties ◽  
Heating Temperature ◽  
Boron Steel ◽  
Hot Press ◽  
Forming Process ◽  
Steel Sheets ◽  
Press Forming ◽  
Bending Process ◽  
Tension Testing ◽  
Hot Press Forming

Bending behavior occurs in the hot press forming process, resulting in many cases of failure during forming. To address the problem of cracking and improve the formability and mechanical properties of boron steel sheets in the bending process, an experiment has been carried out by using a spring compound bending die. Also, a comparison has been made between the traditional U-bending die and the spring compound bending die with regard to formability. The influence of the parameters for hot press forming such as the heating temperature, punch speed, and die radii on the mechanical properties and microstructure was analyzed by tension testing and metallographic observations.

Simulationsgestützte Produktionsplanung flexibler Fertigungssysteme*/Simulation-based production planning of flexible manufacturing systems

2019 ◽  
Vol 109 (04) ◽  
pp. 242-249
Author(s):  
A. Selmaier ◽  
T. Donhauser ◽  
T. Lechler ◽  
J. Zeitler ◽  
J. Franke
Keyword(s):  
Production Planning ◽  
Flexible Manufacturing ◽  
Material Flow ◽  
Flexible Manufacturing Systems ◽  
Manufacturing Systems ◽  
Flow Simulation ◽  
Limited Extent ◽  
Time Data ◽  
High Data ◽  
Simulation Based

Während sich das Verhalten starr verketteter Systeme relativ einfach mittels Materialflusssimulationen modellieren lässt, sind herkömmliche Simulationsansätze für flexible Fertigungssysteme aufgrund des hohen Datenerhebungs- sowie Parametrisieraufwands nur bedingt geeignet. Jedoch kann durch das automatische Übertragen von Echtzeitdaten in das Simulationsmodell der aktuelle Zustand solcher Systeme deutlich verbessert abgebildet werden. Der Beitrag stellt ein Konzept für die simulationsgestützte Produktionsplanung schnellveränderlicher Systeme vor.   While the behaviour of rigidly linked systems is relatively easy to model by means of material flow simulation, traditional simulation approaches are only suitable to a limited extent for flexible manufacturing systems due to the high data collection and parameterization effort. However, the use of real-time data can significantly improve the simulation of such systems. This paper presents an approach for simulation-based production planning of rapidly changing systems.

A Novel Incremental Sheet Bending Process of Complex Curved Steel Plate

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Qiyang Zuo ◽  
Kai He ◽  
Xiaobing Dang ◽  
Wei Feng ◽  
Ruxu Du
Keyword(s):  
Tool Path ◽  
Numerical Control ◽  
Steel Plates ◽  
Work Piece ◽  
Forming Process ◽  
Shipbuilding Industry ◽  
Supporting System ◽  
Motion Modes ◽  
Bending Process ◽  
Curved Steel

Bending complex curved steel plates for constructing ship hull has long been a challenge in shipbuilding industry. This paper presents a novel incremental bending process to obtain complicated curved steel plates by a series of sequential and layered punches. Taking advantage of this process, the blank plate that is fixed and held by a flexible supporting system can incrementally be bent into the target shape by a press tool along a planned tool path step by step and layer by layer. Acting as a “lower die,” the flexible supporting system can provide flexible and multifunctional supports for the work piece during the forming process, whose four general motion modes are demonstrated in this paper. Meanwhile, the procedures of tool path planning and forming layering are also explained in detail. In addition, aiming at different motion modes of the flexible supporting system, two springback compensation methods are given. Furthermore, according to the forming principle presented in this paper, an original incremental prototype equipment was designed and manufactured, which is mainly composed of a three-axis computer numerical control (CNC) machine, a flexible supporting system, and a three-dimensional (3D) scanning feedback system. A series of forming experiments focusing on a gradual curvature shape were carried out using this prototype to investigate the feasibility and validity of this forming process.

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.

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