Simulative basic investigation for a new forming process punch-hole-rolling

Future products will require new forming processes in order to meet the increasing requirements for innovative products. These processes will enable new possibilities in product manufacturing and the control of product properties beyond geometry control. For this purpose, a new process called punch-hole-rolling has been developed, which enables the production of a double-sided collar in thin sheet structures. Punch-hole-rolling is a two-stage process combination of conventional shear cutting and novel rolling which is carried out in one tool. The process combination allows to derive product data from the punching process for the control of the flexible hole-rolling in order to control product properties such as geometry, hardness and microstructure. In order to increase the process understanding and classification, an FE-simulation is built and validated by experiments

The Wooster Voice (Wooster, OH), 1948-02-13

This issue of the Wooster Voice contains a report on Wooster\u27s three-way statewide tie in basketball. Also featured on page 1 are theatre updates, a report on a speech given by Dr. H. Mueller that radiation from atomic bombs may cause human mutation. Reports on Greek life and a course being offered in flying are also present. Page 2 features a piece arguing that fining those who miss Chapel service is detrimental to the Christian project. Also featured are a series of quotes from students asked about their professors, all of which are invariably positive or requesting that the same question be asked once they have graduated. Also present is a gossip column and a piece arguing that students are too concerned with getting a degree and disregard the intrinsic value of an education. Page 3 is the sports section. Page 4 consists entirely of continued articles and advertisements.https://openworks.wooster.edu/voice1941-1950/1163/thumbnail.jp

Soft sensor approach based on magnetic Barkhausen noise by means of the forming process punch-hole-rolling

The relevance of the magnetic Barkhausen noise (MBN) and the non-destructive characterization of material properties in near surface layers, has increased in recent years.With the development of new signal processing techniques, the method was further developed into a powerful evaluation technique and is used in various areas of online and offline measurement. In addition to the established use in the detection of grinding burn, the method is increasingly used in the context of soft sensors for property controlled processes, due to its short analysis times. By a detailed description of a soft sensor concept for the novel forming process punch-hole-rolling this work focuses on the offline characterization of the process specific cause-effect relationships. This is done by analyzing the process interactions as well as the surface layer state by a metallographic investigation. Additionally a non-destructive characterization by means of MBN was done and correlated with the surface layer state. This provides important findings for the use of a MBN-sensor in a soft sensor concept and the potential integration into the forming process

November 28, 1968

https://scholarlycommons.obu.edu/arbn_65-69/1091/thumbnail.jp

In-situ-measurement of the friction coefficient in the deep drawing process

The surface texture plays an important role in the tribological behaviour of deep drawn components. It influences both the process of sheet metal forming as well as the properties for post processing, such as paint appearance, bonding, or corrosion tendency. During the forming process, the texture of the sheet metal and therefore its friction coefficient, changes due to process related strains. This contribution focuses on the development and validation of a tool to investigate the friction coefficient of the flange region of deep drawn components. The influence of biaxial strain on the friction coefficient will be quantified through a comparison of the experimental results with a conventional friction test (stand). The presented method will be applied on a cup drawing test, using a segmented and sensor-monitored blankholder. This setup allows the measurement of the friction coefficient in-situ without simplification of the real process. The experiments were carried out using DX 56D+Z as sheet metal and PL61 as lubricant. The results show a characteristic change in the friction coefficient over the displacement of the punch, which is assumed to be caused by strain induced change of the surface texture

Strain Induced Surface Change in Sheet Metal Forming: Numerical Prediction, Influence on Friction and Tool Wear

In sheet metal forming, free deformation of the sheet takes place frequently without contact with forming tools. The pre-straining resulting from the free deformation leads to a surface roughening of the sheet metal. It is assumed that the roughening has an influence on friction and wear behavior of the following forming process as well as the painting quality after the manufacturing. In this paper, a numerical prediction based on a polycrystalline model is first proposed to predict the effect of surface roughing based on the material data of the as-received state of the sheet metal. Different states of strain are analyzed and the numerical result is validated through experimental evaluation. Besides the numerical prediction, the friction behavior after pre-straining is evaluated in strip drawing tests and the coefficient of friction (COF) is calculated. For interpretation of the measured COF, the surface roughness after the friction test and the surface image are evaluated by a transparent toolset. It is shown that the surface transformation as a result of pre-straining has a negative influence on the lubricating effect of the sheet metal and degrades the friction behavior. Finally, the influence of the strain-induced surface roughening on wear is discussed based on wear testing in strip drawing test with draw bead geometr

Extension of Process Limits in High‐Strength Aluminum Forming by Local Contact Heating

The aluminum alloy EN AW‐7075 T6 is used in the automotive sector for its favorable strength‐to‐weight ratio. However, the limited cold formability is currently addressed by energy‐ and time‐consuming temperature‐assisted processes. In order to limit the effort to critical forming areas only, the state‐of‐the‐art shows promising results for increasing the blank temperature in the range of warm forming. The design of new processes in an industrial context requires appropriate numerical simulation with inherent complexity due to time‐ and temperature‐dependent effects. Herein, the potential of a newly developed tool setup and process chain with integrated local contact heating of the EN AW‐7075 T6 blank is investigated on the basis of a curved hat profile. A thermomechanically coupled FE model of the process is developed and validated. The influence of the local heating layout is analyzed in experimental forming tests and a corresponding process window is derived. The influence of local heating on the occurring failure mechanisms is discussed based on simulation results. The equivalent plastic strain evolution is successfully used to evaluate the local heating dependent failure behavior. A significant increase in the overall formability of the part is achieved by the proposed process chain

Identification of Model Uncertainty via Optimal Design of Experiments Applied to a Mechanical Press

In engineering applications almost all processes are described with the help of models. Especially forming machines heavily rely on mathematical models for control and condition monitoring. Inaccuracies during the modeling, manufacturing and assembly of these machines induce model uncertainty which impairs the controller's performance. In this paper we propose an approach to identify model uncertainty using parameter identification, optimal design of experiments and hypothesis testing. The experimental setup is characterized by optimal sensor positions such that specific model parameters can be determined with minimal variance. This allows for the computation of confidence regions in which the real parameters or the parameter estimates from different test sets have to lie. We claim that inconsistencies in the estimated parameter values, considering their approximated confidence ellipsoids as well, cannot be explained by data uncertainty but are indicators of model uncertainty. The proposed method is demonstrated using a component of the 3D Servo Press, a multi-technology forming machine that combines spindles with eccentric servo drives

A Comparative Study on the Production of a Hat Profile by Roll Forming and Stamping

Lightweight design using high‐strength aluminum alloys has gained importance due to the continuing need for weight reduction and increasing crash safety requirements in the automotive industry. There are various manufacturing processes available for processing high‐strength aluminum alloys. Herein, the production of high‐strength aluminum parts by roll forming and stamping based on the example of an AA7075‐T6 hat profile is compared. Roll forming represents a continuous manufacturing process, while stamping is a discontinuous process. Different process routes (T6, W‐Temper and O) for roll forming as well as for stamping (T6, W‐Temper, O and hot forming) are in focus of the investigation. Fundamental differences of the forming processes and the tempering condition are observed and criteria for the choice of the manufacturing process and process route are presented. The temperature‐supported process routes improve the poor cold formability of AA7075 alloy and thus enhance the process window. Potential is offered for both manufacturing processes by applying tailored properties achieved through targeted quenching