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

November 28, 1968

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

Tool Wear Segmentation in Blanking Processes with Fully Convolutional Networks based Digital Image Processing

The extend of tool wear significantly affects blanking processes and has a decisive impact on product quality and productivity. For this reason, numerous scientists have addressed their research to wear monitoring systems in order to identify or even predict critical wear at an early stage. Existing approaches are mainly based on indirect monitoring using time series, which are used to detect critical wear states via thresholds or machine learning models. Nevertheless, differentiation between types of wear phenomena affecting the tool during blanking as well as quantification of worn surfaces is still limited in practice. While time series data provides partial insights into wear occurrence and evolution, direct monitoring techniques utilizing image data offer a more comprehensive perspective and increased robustness when dealing with varying process parameters. However, acquiring and processing this data in real-time is challenging. In particular, high dynamics combined with increasing strokes rates as well as the high dimensionality of image data have so far prevented the development of direct image-based monitoring systems. For this reason, this paper demonstrates how high-resolution images of tools at 600 spm can be captured and subsequently processed using semantic segmentation deep learning algorithms, more precisely Fully Convolutional Networks (FCN). 125,000 images of the tool are taken from successive strokes, and microscope images are captured to investigate the worn surfaces. Based on findings from the microscope images, selected images are labeled pixel by pixel according to their wear condition and used to train a FCN (U-Net)

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

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

Anmeldelser, bekendtgjort i Statstidende i februar måned.

Anmeldelser, bekendtgjort i Statstidende i februar måned

Tribology in Warm and Hot Aluminum Sheet Forming: Transferability of Strip Drawing Tests to Forming Trials

For conventional sheet metal forming at room temperature, numerous tribometers have been developed in the 20th century. At the present state of the art, there are some challenges for tribometry in warm and hot forming processes of high‐strength aluminum (e.g., EN AW‐7075). Especially for nonisothermal processes with heated sheets and cooled dies, the tribological design is a major challenge, which needs to be addressed by investigations with adapted tribometers. Herein, the transferability of friction and wear behavior of three different lubricants and temperatures is investigated. Therefore, tribometer test results are compared with real forming trials in combination with thermomechanical finite element simulations. Both the behavior of different lubricant types and the characteristics of tool lubrication in sheet metal forming are discussed

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