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Instrumentirana naprava za analizo vedenja kovinskih prahov med hladnim enoosnim stiskanjem
Šuštaršič, Borivoj (Author), Kosec, Ladislav (Author), Špan, Tomaž (Author), Jelenko, Milan (Author), Torkar, Matjaž (Author)

URLURL - Presentation file, Visit http://www.dlib.si/details/URN:NBN:SI:DOC-VWVJDESW This link opens in a new window

Abstract
Razvili in izdelali smo instrumentirano celico za analizo vedenja kovinskih in keramičnih prahov med njihovim hladnim enoosnim stiskanjem. Celica je vgrajena v univerzalni servo-hidravlični preizkuševalni stroj Instron 1255, ki nam v tem primeru rabi kot enoosna stiskalnica. Celoten sistem omogoča tudi ugotavljanje vedenja stiskanca (surovca) pri njegovem izmetavanju iz orodja kot tudi določitev njegovih trdnostnih lastnosti. Z razvito programsko opremo je bilo omogočeno zajemanje vseh merjenih veličin, njihova obdelava, izračun osnovnih medsebojnih odvisnosti ter njihova vizualna in grafična predstavitev. Sistem lahko koristno uporabimo tudi za določitev tlačne preoblikovalne trdnosti konvencionalnih kovinskih materialov. V prispevku predstavljamo samo napravo in nekaj eksperimentalnih rezultatov, dobljenih z novo napravo med enoosnim stiskanjem vodnoatomiziranih jeklenih prahov. Predstavljamo tudi sistem, ki omogoča določevanje tlačne preoblikovalne trdnosti v odvisnosti od stopnje deformacije konvencionalnih kovinskih materialov.

Language:Slovenian
Keywords:kovinski prahovi, hladno enoosno stiskanje, laboratorijski preizkusi
Work type:Not categorized (r6)
Tipology:1.01 - Original Scientific Article
Organization:NTF - Faculty of Natural Sciences and Engineering
Year:2001
Publisher:Inštitut za kovinske materiale in tehnologije
Number of pages:str. 351-360
Numbering:Letn. 35, št. 6
UDC:621.762.4:620.17:519.68
ISSN on article:1580-2949
COBISS.SI-ID:328799 Link is opened in a new window
Views:370
Downloads:80
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Record is a part of a journal

Title:Materiali in tehnologije
Shortened title:Mater. tehnol.
Publisher:Inštitut za kovinske materiale in tehnologije
ISSN:1580-2949
COBISS.SI-ID:106193664 This link opens in a new window

Secondary language

Language:English
Title:An instrumented cell to analyse the behaviour of metal powders during cold uniaxial die compaction
Abstract:
The densification of metal powders via automatic uniaxial die compaction in hydraulic or mechanical presses is a very important operation in standard P/M manufacturing procedures for sintered metal parts with complex shapes. Consequently, a knowledge of how the metal powders behave during cold compaction is very important for the development of new powdered materials andthe manufacturing optimisation of sintered parts. Recently, some computer models have been developed which enable the successful prediction and simulation of the dynamic behaviour of powders during their compaction and ejection from the die. The models are used to calculate a series of process parameters that are important for the optimum powder compaction into the complex compact, for the dimensioning of the dies and presses and for the prediction of the die life. The reasons for crack formation inside the compact can also be analysed. An instrumented die is used for the exact experimental determination of the parameters and the data needed for the determination of the appropriate constitutive law which describes the powder/compact behaviour during the compaction/ejection. Actuators and sensors are connected to a computer and adequate hardware/software is used for the continuous, fast and accurate acquisition, processing, and analysis of the measured data. The complete analysis and determination of all constitutive parameters requires a complex instrumented die (cell) in which the powder is subjected to a 3D stress field. Recently, it has been proved that it is possible to obtain enough experimental data with a simpler instrumented cylinder die in which the investigated powder is compressed uniaxially. The die must be incorporated into the press, which makes it possible to control the compaction of the powders up to high pressures (800-900 MPa) and relatively high green densities (above 95% of T.D.). This kind of equipment allows us to determine all the experimental data which describe the behaviour of a new or existing powder material during compaction, and allows the analysis and experimental validation of a certain model, or the starting points for the development of a new model. A new instrumented cell for the analtsis of metal and ceramic powders during uniaxial cold compaction was developed at the Institute of Metals and Technology, Ljubljana. The cell was incorporated into a universal 500 MPa Instron 1255 (UK) servo-hydraulic testing machine which serves as a uniaxial press. The complete system also allows us to analyse the behaviour of the compact during its ejection, as well as to determine the compacts' green strength. The developed software allows us to continuously collect and process all the measured values and calculate the basic relationships and present them graphically. In this article we present the new equipment and some experimental results obtained during the compaction of water-atomised steel powders. The system can also be used independently for the determination of the compaction true-stress-strain curves of conventional materials. Therefore, some experimental results from this area are also presented.

Keywords:metal powders, uniaxial die compaction, laboratory testing

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