Description of the contact between a deterministic anisotropic tool surface and a workpiece subjected to plastic deformation

1998 ◽  
Vol 212 (5) ◽  
pp. 403-409 ◽  
Author(s):  
M-I Rotarescu
Keyword(s):  
Metal Forming ◽  
Inverse Method ◽  
Sliding Friction ◽  
Critical Issue ◽  
The Finite Element Method ◽  
Contact State ◽  
Tool Surface ◽  
Grooved Surface ◽  
Workpiece Interaction ◽  
Upsetting Test

The finite element method offers an opportunity to obtain important information by simulating metal-forming processes. The description of the tool—workpiece interaction still remains a critical issue. The aim of this paper is to describe the contact between a deterministic anisotropic tool surface (grooved) and a workpiece. This is done by means of an existing contact processor and a friction law that has been conceived to describe sliding friction. This compromise solution of describing a contact state near to sticking by means of a law created for sliding friction is investigated. The results obtained using a macrogeometric model of the grooved surface are compared to those achieved by an idealized smooth surface and different friction coefficients. Next, an anisotropic model is introduced and calibrated using the inverse method based on the ring upsetting test for a hot-worked steel.

Metal Forming and the Finite-Element Method

1989 ◽  
Author(s):  
Shiro Kobayashi ◽  
Soo-Ik Oh ◽  
Taylan Altan
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Metal Forming ◽  
Computer Aided Design ◽  
The Finite Element Method ◽  
Forming Technology ◽  
Computer Aided ◽  
Deformation Mechanics ◽  
Aided Design ◽  
Element Method

The application of computer-aided design and manufacturing techniques is becoming essential in modern metal-forming technology. Thus process modeling for the determination of deformation mechanics has been a major concern in research . In light of these developments, the finite element method--a technique by which an object is decomposed into pieces and treated as isolated, interacting sections--has steadily assumed increased importance. This volume addresses advances in modern metal-forming technology, computer-aided design and engineering, and the finite element method.

Gleitreibung der tribologischen Paarung CFK – Werkzeugschneidenoberfläche*/Sliding friction of the tribological pair of CFRP / tool cutting surface

2017 ◽  
Vol 107 (01-02) ◽  
pp. 81-86
Author(s):  
T. Stehle ◽  
B. Prof. Azarhoushang ◽  
D. Becker ◽  
R. Eisseler
Keyword(s):  
Sliding Friction ◽  
Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Test Tool ◽  
Cutting Surface ◽  
Surface Topographies ◽  
Tool Surface ◽  
Strip Drawing ◽  
And Function ◽  
Tool Cutting

Die Reibungsbedingungen bei der Zerspanung von verstärkten Faserverbundkunststoffen werden durch die Oberflächengestalt der Werkzeugschneide beeinflusst. In dieser Studie wurde CFK-UD (unidirektional carbonfaserverstärkter Kunststoff) im Streifenziehversuch mit geschliffenen und gestrahlten Testwerkzeugen bei 5 MPa Flächenpressung untersucht. Die Oberflächen der Testwerkzeuge sind durch bestimmte Rauheits- und Funktionsparameter charakterisiert, die sich auf die Gleitreibung der tribologischen Paarung CFK – Werkzeugschneide auswirken.   The friction conditions when cutting fiber-reinforced polymers are significantly influenced by the shape of the tool cutting surface. Hence, different strip drawing tests were carried out at a 5 MPa surface pressure to investigate the behavior of unidirectional CFRP with different test tool surface preparations. The tool surfaces were ground and blasted. The created surface topographies are characterized by particular parameters of roughness and function which affect the sliding friction of the CFRP / tool pair.

Tool Surface Topographies for Controlling Friction and Wear in Metal-Forming Processes

1998 ◽  
Vol 120 (3) ◽  
pp. 517-527 ◽  
Author(s):  
Simon Sheu ◽  
Louis G. Hector ◽  
Owen Richmond
Keyword(s):  
Surface Topography ◽  
Metal Forming ◽  
Friction And Wear ◽  
Workpiece Surface ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Single Scale ◽  
Surface Topographies ◽  
Tool Surface ◽  
Scale Surface

A conceptual framework is introduced for the design of tool surface topographies in bulk metal forming processes. The objective of the design is to control friction to desired levels while minimizing wear of the workpiece and tool surfaces and adhesive metal transfer between the workpiece and tool. Central to the design framework are the tool/workpiece interface properties of lubricant retention and interface permeability. Lubricant retention refers to the capacity of an interface to retain lubricant rather than freely channel it to the exterior of the tool/workpiece conjunction. Permeability refers to the capacity to distribute lubricant to all areas within the conjunction. These properties lead to the concept of two-scale surface topography consisting of a fine scale background of interconnected channels on which is superimposed an array of coarser-scale cavities. Control of friction and wear is achieved by designing the tool surface topographies at these two scales to address the unique tribological conditions of specific bulk metal forming processes. The coarser scale is designed to ensure adequate supply of lubricant within the conjunction. The finer scale is designed to ensure adequate delivery of lubricant to all parts of the conjunction where nascent workpiece surface is being formed. The design concepts are illustrated with results from laboratory experiments using the rolling process as an example, and comparing the performance of various roll surface topographies under similar processing conditions. A two-scale surface topography consisting of hemispherical cavities distributed across a background surface of finer scale, interconnected channels was shown to reduce friction compared to a single-scale ground finish, but not as much as a single-scale coarse topography consisting of densely-packed cavities produced by an electrical discharge treatment. On the other hand, the smoother cross-sections of the cavities, especially when elongated in the direction of greatest relative motion, produced significantly less wear than either of the single-scale tool surface treatments. It is concluded that two-scale engineering of tool surface topographies based upon the concepts of lubricant retention and interface permeability can provide a broad basis for achieving desired levels of interface friction while minimizing workpiece surface wear and adhesive material transfer in many metal-forming processes.

Experimental Analysis of Velocity Fields in Hot Extrusion of Aluminium Alloy 6351

2011 ◽  
Vol 491 ◽  
pp. 145-150 ◽  
Author(s):  
Marcelo Martins ◽  
Sérgio Tonini Button ◽  
José Divo Bressan
Keyword(s):  
Metal Forming ◽  
Internal Flow ◽  
Hot Extrusion ◽  
Experimental Tests ◽  
Velocity Fields ◽  
The Finite Element Method ◽  
Forming Process ◽  
Complex Shapes ◽  
Metal Forming Process ◽  
Volume Method

Hot extrusion is a metal forming process with a huge importance in the manufacturing of long metallic bars with complex shapes, and because of this, academics and industries are especially interested in better understanding how metal flows during the process. In order to have a reliable computational tool that can help to solve and to obtain material internal flow, experimental tests and numerical simulation with the finite element method were carried out to obtain results of the velocity fields generated in hot direct extrusion of aluminum billets (aluminum alloy 6351). The experimental results of the velocity field will be used to validate a computational code based on the finite volume method.

scholarly journals Tool surface with a supporting plateau of hard particles for deep drawing of high alloy steel

2018 ◽  
Vol 190 ◽  
pp. 14006 ◽  
Author(s):  
Hannes Freiße ◽  
Thomas Seefeld
Keyword(s):  
Sheet Metal Forming ◽  
Deep Drawing ◽  
Metal Forming ◽  
Adhesive Wear ◽  
High Alloy ◽  
High Alloy Steel ◽  
Hard Particles ◽  
Aluminium Bronze ◽  
Tool Surface ◽  
Alloy Steels

Sheet metal forming normally requires the application of lubricants to protect the tool and the sheet against wear. The parts must be cleaned to remove the lubricants before joining and coating. This process step wastes energy and water resources. In the case of non-lubricated sheet metal forming, cleaning processes would not be necessary anymore and the process chain could be optimized regarding ecological and economical aspects. However, forming without lubrication leads to an intensive contact between the tool and the sheet. Thus, higher wear occurs and process reliability cannot be ensured for industrial mass production. High alloy steels are applied for mass-market products e.g. for appliances. Because of the higher strength, strain hardening and galling effects the austenitic steels are comparatively difficult to form. For dry metal forming of high alloy steels new tool concept must be developed to withstand the higher loads. In this work, a laser generated tool surface with a supporting plateau of hard particles (metal matrix composite (MMC-surface)) is presented. Spherical fused tungsten carbides were injected into the surface by laser melt injection. The metallic matrix of the composite was rejected by applying laser ablation. In consequence, the hard particles stood out of the matrix and were in direct contact with the sheet material. The surface of hard particles had a high hardness about 3000 HV and less metallic character. Cold working steel and aluminium bronze were tested as reference tool materials. Dry and lubricated forming experiments were carried out by strip drawing with bending and deep drawing of cups. Dry deep drawing of cups was not possible by using cold work tool steel. This can be traced back to the occurrence of wrinkles and cup base fracture at the same time. Applying aluminium bronze as tool material for dry metal forming resulted in high adhesive wear. Within this work the feasibility of dry metal forming of high alloy steel could be demonstrated by applying the MMC-surface whereby adhesive wear could be reduced.

Development of Parametric Simulation Models for Metal Forming Processes of Plate Structures

2018 ◽  
Author(s):  
Tom Wurzler ◽  
Thomas Lindemann ◽  
Josefine Kistner ◽  
Patrick Kaeding
Keyword(s):  
Metal Forming ◽  
Simulation Models ◽  
Metal Plate ◽  
The Finite Element Method ◽  
Forming Process ◽  
Common Procedure ◽  
Plate Structures ◽  
Metal Plates ◽  
Die Structure ◽  
Different Types

During the process of workpiece productions in metal forming industries, it is necessary to control the results of the reshaped piece to ensure its quality. A common procedure of metal plate forming processes is given by the application of an upper and lower die. Therefore, ribbed die configurations can be used. To simulate the forming process of metal workpieces, the Finite Element Method (FEM) is a feasible tool. In this paper, a parametric model of a ribbed die structure is developed with the specification that only small imperfections on the workpiece surfaces will appear after the forming process. The workpieces in this paper are plates with thickness values equal and greater than 20mm. Furthermore, the springback behaviour of the different workpieces will be in the main focus of the proposed analyses. The results of the simulations are used to developed different types of holder configurations instead of the lower die. This concept might further reduce the costs of forming processes of large metal plates.

scholarly journals Lubrication Analysis of Micro-Dimple Textured Die Surface by Direct Observation of Contact Interface in Sheet Metal Forming

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 917 ◽  
Author(s):  
Shimizu ◽  
Kobayashi ◽  
Vorholt ◽  
Yang
Keyword(s):  
Metal Forming ◽  
High Speed ◽  
Sliding Friction ◽  
Flow Analysis ◽  
Hydrodynamic Pressure ◽  
Observation System ◽  
In Situ Observation ◽  
Two Phase ◽  
Micro Dimple

: To investigate the underlying mechanism of the effects of surface texturing on lubricated sliding friction in the metal forming operation, an in-situ observation system using transparent silica glass dies and a high speed recording camera was newly developed. To correlate the dimensional parameters of micro-dimple textured structures and tribological properties in the metal forming operation, the in-situ observation was performed during bending with the ironing process of the stainless steel sheet with a thickness of 0.1 mm. The lubrication behavior were compared between the different lubricant viscosities and the micro-dimple textures with different diameters of 10 µm, 50 µm, 100 µm fabricated by using femto-/pico-second laser processing. As a result, the textured die with dimple diameters of 10 µm and 50 µm showed the lubricant flow transferred from one to the other dimples owing to the lubricant reservoir effect, while that of 100 µm indicated the less supply of the lubricant. However, the textured die with a dimple diameter of 10 µm demonstrated higher ironing force than that of 50 µm, due to the severe adhesion of work materials inside the dimple structures. Based on these experimental findings, the dimple size dependencies on lubricant reservoirs effects and the generation of the hydrodynamic pressure were discussed by correlating with the in-situ observation results, a fluid-flow analysis and a laminar two-phase flow analysis using the finite element method.

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