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1

Flexible system for micro-clinching processes design and analysis

Presz Wojciech, Bing-Yuan Han

Welding Technology Review

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2020

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R. 92, nr 4

31--45

EN

With the development of microprocessors, actuators and structural micro-components, new concepts of micro-electro-mechanical systems/machines are constantly being introduced. One of the consequences of this tendency is seeking for best techniques to connect metal micro-components. Because of tools simplicity, no additional fastening parts and the undisturbed structure of the material, clinching appears to be a promising method for joining in micro-scale. A procedure for the analysis of micro-clinching process is proposed in the paper, and unique, support flexible tooling system designed. This system allows to easily change key parameters of the process. With the use of flexible micro-tooling, a successful micro-clinching of silver sheets of thickness 0.18 mm has been conducted. An effective numerical method - Rapid Numerical Strength Test - for modelling the process of tearing the joints has been presented. Compliance of key phenomena recognized in modelling with experimental results was obtained.

PL

Wraz z rozwojem mikroprocesorów, siłowników i mikroskładników strukturalnych stale wprowadzane są nowe koncepcje systemów/maszyn mikroelektromechanicznych. Jedną z konsekwencji tej tendencji jest poszukiwanie najlepszych technik łączenia mikrokomponentów metalowych. Biorąc pod uwagę prostotę narzędzi, brak dodatkowych elementów mocujących i niezakłóconą strukturę materiału, klinczowanie wydaje się być obiecującą metodą łączenia w mikroskali. W artykule zaproponowano procedurę analizy procesu mikro-klinczowania oraz zaprojektowano unikalny, wspierający elastyczny system narzędziowy. System ten pozwala na łatwą zmianę kluczowych parametrów procesu. Dzięki zastosowaniu elastycznego mikro-oprzyrządowania przeprowadzono udane mikro-klinczowanie blach srebrnych o grubości 0,18 mm. Przedstawiono skuteczną metodę numeryczną - Rapid Numerical Strength Test - do modelowania procesu rozrywania złączy. Uzyskano zgodność kluczowych zjawisk rozpoznanych w modelowaniu z wynikami eksperymentalnymi.

2

Ultrasonic vibrations as an impulse for glass transition in microforming of bulk metallic glass

Presz Wojciech, Kulik Tadeusz

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 1

100--113

EN

The paper presents the idea of the utilisation of ultrasonic vibrations in microforming at elevated temperature of a bulk metallic glasses as an impulse of additional energy for initiating a glass transition at lower than nominal temperature. The method of micro-upsetting at elevated temperature with non-uniform temperature distribution (MUNUT) was used. It is shown that applying ultrasonic vibrations on the tool could replace the part of the thermal energy needed for achieving the supercooled liquid state necessary for the microforming of bulk metallic glass. The results of research are limited to the analysis of two micro-specimens only and their final state of deformation. The commercial FEM code was used in the Thermal/Structural analysis class to determine the temperature distribution within the micro-specimen and to justify the linear approximation of this distribution. It was shown that the application of ultrasonic vibrations at 20 kHz frequency and the amplitude PP = 36.5 μm under the experiment conditions lowered the transformation temperature by approx. 32 °C. Results suggesting that applying ultrasonic vibrations could be also used as the tool which would provide additional energy for the transformation at the limited area of the micro-product.

3

Heading of a small bi-metallic components for electric contacts

Presz Wojciech, Cacko Robert

Computer Methods in Materials Science

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2018

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Vol. 18, No. 2

41--48

EN

Electrical connectors mostly have silver contacts joined to the supplying and discharging electric current elements by riveting. In order to reduce costs, the rivet core of the contact can be replaced with a cheaper material such as copper. There is a wide range of commercially offered bi-metallic, silver-copper rivets available for the production of contacts. This generates a new situation in the riveting process, as the bi-metallic rivet is to be formed. In the analyzed example it is a small-sized object that places it near the limits of micro-forming. The riveting process was originally designed by classical upsetting. It was based on the results of FEM simulation taking into account the deformation of three materials included in the joint: two materials for rivet and sheet material. The FEM results were verified by the results of experimental studies indicating high compliance. The elimination method of the elastic deformations of the load system impact on the process forces was elaborated and it was used for comparative analysis with the force run obtained from FEM. The model simulating the working conditions of the connector was developed. Based on the joint load modeling results, the cause of possible delamination of constituent materials was determined. It was also defined the desired silver distribution in the connector head to eliminate the risk of separation of both materials during exploitation.