scholarly journals One Contribution to the Friction Investigation in Bulk Metal Forming

2011 ◽  
Vol 36 (1) ◽  
pp. 35-48 ◽  
Author(s):  
Igor Kačmarčik ◽  
Dejan Movrin ◽  
Aljoša Ivanišević
Keyword(s):  
Sheet Metal ◽  
Relative Motion ◽  
Metal Forming ◽  
Negative Impact ◽  
Ring Test ◽  
Main Process ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Backward Extrusion ◽  
Twist Extrusion

One Contribution to the Friction Investigation in Bulk Metal Forming Friction is resistance to relative motion when one body slides over another. In metal forming operations, both sheet metal and bulk metal forming, friction is undesirable but also unavoidable occurrence. It has negative impact on main process parameters as well as on workpiece quality. In order to obtain accurate results in metal forming experiments or simulations, the precise value of friction has to be known. In this paper several methods for friction evaluations, such as ring test, forward bar extrusion, backward - forward hollow extrusion, twist extrusion are presented and analyzed. A new double backward extrusion model is proposed.

scholarly journals Extension of the forming limits of extrusion processes in sheet-bulk metal forming for production of minute functional elements

2020 ◽  
Vol 7 ◽  
pp. 9 ◽  
Author(s):  
Florian Pilz ◽  
Johannes Henneberg ◽  
Marion Merklein
Keyword(s):  
Sheet Metal ◽  
Metal Forming ◽  
Extrusion Process ◽  
Process Conditions ◽  
Functional Elements ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Lateral Extrusion ◽  
Component Design ◽  
Tailored Surfaces

Increasing demands in modern production pose new challenges to established forming processes. One approach to meet these challenges is the combined use of established process classes such as sheet and bulk forming. This innovative process class, also called sheet-bulk metal forming (SBMF), facilitates the forming of minute functional elements such as lock toothing and gear toothing on sheet-metal bodies. High tool loads and a complex material flow that is hard to control are characteristic of SBMF. Due to these challenging process conditions, the forming of functional elements is often insufficient and necessitates rework. This negatively affects economic efficiency. In order to make use of SBMF in industrial contexts, it is necessary to develop measures for improving the forming of functional elements and thereby push existing forming boundaries. This paper describes the design and numerical replication of both a forward and a lateral extrusion process so as to create involute gearing in combination with carrier teeth. In a combined numerical-experimental approach, measures for extending the die filling in sheet-metal extrusion processes are identified and investigated. Here, the focus is on approaches such as process parameters, component design and locally adjusted tribological conditions; so-called ‘tailored surfaces’. Based on the findings, fundamental mechanisms of action are identified, and measures are assessed with regard to their potential for application. The examined approaches show their potential for improving the forming of functional elements and, consequently, the improvement of geometrical accuracies in functional areas of the workpieces.

Sheet-Bulk Metal Forming of Preformed Sheet Metal Parts

2011 ◽  
Vol 473 ◽  
pp. 83-90 ◽  
Author(s):  
Thomas Schneider ◽  
Marion Merklein
Keyword(s):  
Sheet Metal ◽  
Deep Drawing ◽  
Metal Forming ◽  
Sheet Plane ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Sheet Metal Parts ◽  
Bulk Forming ◽  
Process Factors ◽  
Functional Components

Due to ecological and economic challenges there is a rising demand on closely-tolerated complex functional components. Regarding short process chains and improved mechanical properties conventional forming processes are often limited. A promising approach to meet these requirements can be seen in the combination of traditional sheet and bulk metal forming processes, to form sheet metals out of the sheet plane with typical bulk forming operations. The challenge of applying conventional bulk forming operations on sheet metal is the interaction between regions of high and low deformation, which is largely unknown in literature. To analyze this topic fundamentally, a process combination of deep drawing and upsetting is developed for manufacturing tooth-like elements at pre-drawn cups. To fully understand material flow out of the sheet plane into the tooth cavity and to identify and qualify process factors depending on the functional elements´ geometry and friction, a single upsetting stage forming a simplified model of the blank is virtually analyzed with finite-element simulation. By inhibiting the forming history of the pre-drawn blank, the upsetting process can be investigated without interactions with a previous deep drawing operation.

Blech-Massiv-Umformung genauer Getriebekomponenten*/Sheet-bulk metal forming of high-precision gear components – Manufacturing of multi-tooth hollow components by cold forging a semi-finished sheet metal product

2017 ◽  
Vol 107 (10) ◽  
pp. 683-688
Author(s):  
M. Prof. Liewald ◽  
A. Felde ◽  
R. Neher
Keyword(s):  
Sheet Metal ◽  
High Precision ◽  
Experimental Work ◽  
Metal Forming ◽  
Metal Product ◽  
Cold Forging ◽  
Positional Accuracy ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Metal Material

Der Fachbeitrag beschreibt numerische und experimentelle Arbeiten zur Entwicklung einer Stadienfolge und einzelner Umformstufen in der Fertigung eines Versuchsbauteils mit zwei Außenverzahnungen und einem inneren Verzahnungsprofil, ausgehend von einer Ronde aus Blech. Im Zuge der Untersuchung wurde bestätigt, dass der Einsatz eines in der Dicke eng tolerierten, flachen Halbzeugs aus Blechmaterial signifikante Vorteile für die erreichbare Lagegenauigkeit bei der Herstellung hohler Pressteile mit Verzahnungen mit sich bringen kann.   This paper is about numerical and experimental work for developing a calibration sequence and individual forming operations to produce a hollow specimen with two external teeth and an internal toothed profile, starting from sheet metal material. The investigation shows that the application of an accurate, flat-shaped semi-finished sheet product can lead to significant advantages regarding the achievable positional accuracy in the production of such hollow press parts.

Material Flow in Sheet-Bulk Metal Forming

2012 ◽  
Vol 504-506 ◽  
pp. 1035-1040 ◽  
Author(s):  
Ulrich Vierzigmann ◽  
Johannes Koch ◽  
Marion Merklein ◽  
Ulf Engel
Keyword(s):  
Sheet Metal ◽  
Metal Forming ◽  
Material Flow ◽  
Fe Simulation ◽  
Forming Process ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Mould Filling ◽  
Model Geometry ◽  
Functional Components

Innovative trends like increasing component functionality, the demand for automotive lightweight constructions and the economic issue to optimize existing process chains, require new ways in manufacturing. Today, the traditional sheet metal and bulk metal forming processes are often reaching their limits if closely-tolerated complex functional components with variants have to be produced. A promising approach is the direct forming of high-precision shapes starting from blanks. Thus, classic sheet metal forming operations, such as deep drawing, are combined with bulk metal forming operations like extrusion of complex variants as for example teeth. This combination of sheet and bulk metal forming operations leads to a side by side situation of different tribological conditions according to the locally varying load situations within the same forming process. This new class of forming processes is defined as sheet-bulk metal forming (SBMF). The tribological conditions in sheet-bulk metal forming processes are of major importance for the process realization, its stability and for the quality of the produced part. The objective of this paper is the investigation of material flow in SBMF in general and the attempt to improve the material flow by local adapted tribological conditions. First the material flow was analyzed by FE-simulation of a model geometry that is typical for SBMF. The investigations with FE-simulation have shown, locally adapted tribological conditions are leading to an improvement in material flow and thus to an increased mould filling. As frictional conditions are directly connected to the topography of workpiece and tool, the modification of the workpiece topography is leading to an alteration in friction values. For the modification of workpiece topography grit blasting was used. The increase in friction of grit blasted surface towards untreated surface was investigates by using the laboratory friction tests. To manufacture specimens with locally adapted topographies for forming tests a masking technique has been developed. The masks are designed after the preliminary findings determined by FE-simulation.

scholarly journals Influence of component design on extrusion processes in sheet-bulk metal forming

2019 ◽  
Vol 13 (6) ◽  
pp. 981-992 ◽  
Author(s):  
F. Pilz ◽  
M. Merklein
Keyword(s):  
Sheet Metal ◽  
Metal Forming ◽  
Experimental Approach ◽  
Functional Integration ◽  
Dimensional Accuracy ◽  
Design Parameters ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Bulk Forming ◽  
Component Design

Abstract Nowadays, the functional integration of workpieces challenges existing forming processes. The combination of established forming processes – like sheet metal and bulk forming – offers the possibility to counter this issue. The application of bulk forming operations on sheet metal semi-finished products, also called sheet-bulk metal forming (SBMF), is an innovative approach. The potential of SBMF cannot be fully exploited, as there are no recommendations in terms of workpiece design and layout influence on the process result. Therefore, this paper focuses on the analysis of semi-finished products and component design parameters on resulting part and process properties in two extrusion processes in SBMF. The investigation is based on a combined numerical and experimental approach. It is shown that the investigated design parameters, in addition to the achievable dimensional accuracy, substantially influence the occurring tool loads as well as the required process forces.

scholarly journals Influence of Tailored Surfaces and Superimposed-Oscillation on Sheet-Bulk Metal Forming Operations

2020 ◽  
Vol 4 (2) ◽  
pp. 41
Author(s):  
Bernd-Arno Behrens ◽  
Wolfgang Tillmann ◽  
Dirk Biermann ◽  
Sven Hübner ◽  
Dominic Stangier ◽  
...  
Keyword(s):  
Sheet Metal ◽  
Metal Forming ◽  
High Strength Steels ◽  
High Strength ◽  
Compression Tests ◽  
Forming Process ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Tailored Surfaces ◽  
High Feed

Producing complex sheet metal components in fewer process steps motivated the development of the innovative forming process called sheet-bulk metal forming (SBMF). In this process, sheet metal forming and bulk-metal forming are combined to create a unique forming process in which a component with external and internal gearing is produced in three production steps. However, the high degrees of deformation that occur using high-strength steels and the number of different process steps result in high process forces, strongly limiting the service life of tools. To reduce the forming force during SBMF processes, tool and process modifications were investigated. Therefore, plane-strain compression tests were conducted to examine the influence of a CrAlN PVD coating and tailored surfaces produced by high-feed milling (HF) of tool-active elements on the material flow of the specimens. In addition to the tool-sided modifications, the influence of an oscillation overlay during the forming process was investigated. Based on the results of the compression tests, the surfaces of the active tool elements of the SBMF process were modified in order to transfer the basic experimental results to the production of a functional component. The friction is thus adapted locally in the SBMF process.

scholarly journals Development of a numerical compensation framework for geometrical deviations in bulk metal forming exploiting a surrogate model and computed compatible stresses

2021 ◽  
Author(s):  
Lorenzo Scandola ◽  
Christoph Büdenbender ◽  
Michael Till ◽  
Daniel Maier ◽  
Michael Ott ◽  
...  
Keyword(s):  
Finite Element ◽  
Surrogate Model ◽  
Metal Forming ◽  
Computer Aided Design ◽  
Transition Process ◽  
Reference Points ◽  
Compensation Method ◽  
Tool Geometry ◽  
Bulk Metal ◽  
Bulk Metal Forming

AbstractThe optimal design of the tools in bulk metal forming is a crucial task in the early design phase and greatly affects the final accuracy of the parts. The process of tool geometry assessment is resource- and time-consuming, as it consists of experience-based procedures. In this paper, a compensation method is developed with the aim to reduce geometrical deviations in hot forged parts. In order to simplify the transition process between the discrete finite-element (FE) mesh and the computer-aided-design (CAD) geometry, a strategy featuring an equivalent surrogate model is proposed. The deviations are evaluated on a reduced set of reference points on the nominal geometry and transferred to the FE nodes. The compensation approach represents a modification of the displacement-compatible spring-forward method (DC-SF), which consists of two elastic FE analyses. The compatible stress originating the deviations is estimated and subsequently applied to the original nominal geometry. After stress relaxation, an updated nominal geometry of the part is obtained, whose surfaces represent the compensated tools. The compensation method is verified by means of finite element simulations and the robustness of the algorithm is demonstrated with an additional test geometry. Finally, the compensation strategy is validated experimentally.

Fundamental investigations on the material flow at combined sheet and bulk metal forming processes

CIRP Annals ◽  
2011 ◽  
Vol 60 (1) ◽  
pp. 283-286 ◽  
Author(s):  
M. Merklein ◽  
J. Koch ◽  
S. Opel ◽  
T. Schneider
Keyword(s):  
Metal Forming ◽  
Material Flow ◽  
Bulk Metal ◽  
Bulk Metal Forming
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