Euro PM13+EP13074+Cristinel Besleaga

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Ways to reduce the wear of the excavation equipment by application of PM

C. Besleaga1, R.M. Negriu1, I. Popescu1,S.G. Badea1,1)Econet Prod Bucharest, Pades street no. 16, Bucharest, Romania

[email protected] ;

AbstractWear occurs with high intensity in the excavation equipment of heavy railway machines for cleaningthe crushed stone, providing a large area of applications using new PM materials and PMtechnologies. These machines are very important for railway infrastructure maintenance. The purposeis to reduce the intensity of wear and increase lastingness, with direct effect in reducing the cost ofthese very expensive pieces. Researches conducted (including CAD-FEM methods) try to ensure thatthe introduction of PM hard material and the applications of PM technology will not affect theresistance of the excavation chain.

Keywords: railway cleaning machine, wear, PM materials, CAD-FEM

1. Introduction

The maintenance of railway infrastructure includes various technological processes tomaintain geometrical parameters and the qualities of elasticity and permeability of crushed stoneprism. One of the technological operations of railway maintenance that is performed mechanized iscleaning of the crushed stone from prism of railway infrastructure [1, 2]. This technological operation isdone by cleaning railway machines [3], such as that of Fig. 1.

Fig.1: Railway cleaning machine type RM 80 UHR (left) andthe excavation installation with chain excavator (right)

The installation of excavation of cleaning machines with chain excavator is one of the moststress components of these machines [4, 5].

Fig.2: The main element of chain excavator: 1-scraper bolt with CW body; 2-scraper shovel;3- Connecting chain link; 4- join bolt.
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2. Wear of the lower edge of the scraper shovel and connecting chain links

From experimental studies and researches we have found a special form of wear of the maincomponents of the chain excavator (in this case scraper shovel and connecting chain links). This

special form of wear is found on the chain excavator guide (gutter) and the chain excavator himself(Fig.3)

Fig.3: Chain excavator guide (gutter)- left; chain excavator in chain guide right;

This wear is caused by waste material type powder that accumulates behind chain excavatoron the chain guide (gutter) even in corner. To avoid filling with the waste powder material the chainguide (gutter) is made with special windows (exhaust holes)- Fig.4.

Fig.4: Window (hole) in chain excavator guide (gutter) for evacuation of waste material

These windows (holes) are insufficient to discharge the waste powder material dueconstructive, functional and strength conditions. The waste powder material becomes very hard,compacts and abrasive (Fig.5- black arrow).

Fig.5: The waste powder material (black arrows) and the wear of corner (edge) of scraper shovel inchain guide (gutter)


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One of special area is wear on the chain guide that determine the "rounding" of the lower edgeof the scraper shovel and connecting chain links (Fig. 6).

Fig.6: Wear by rounding of the lower edge of the connecting chain links

3. Analyses CAD-FEM of main components of chain excavator

For installation of composite material bodies produced by powder technology it was made theanalyses CAD-FEM [4, 5] (Fig.7, 8). These researches [6, 7] have led to the mounting solution ofcomposites sintered metallic carbide only to the connecting chain links to avoid decreasing strengthand breakage oh the chain excavator.

Fig.7: The stress state determined with CAD-FEM analyze in chain excavator


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Fig.8: The stress state in connecting chain link (left) and scraper shovel (right)

Fig.9: CMS bodies mounted in connecting chain links (red arrows)

The research has led to the installation of the CMS bodies in the lower edge of connectingchain links (Fig. 9), in order to "cut", clean and avoid the submission and training hard layer ofpowdered material derived from "grinding" broken stone, tailings and other wastes in light of existingthe excavated stone and chain.

4. Applications of hard PM materials to the scrapers of cleaning machines

Wear resistant bodies [8, 9] (shock and abrasion) were made of composite materials (CW-Co,CW-Ni, CW-(W-Ti ) C-Ni), obtained by sintering and procedures specific to powder metallurgy. Highdensity bodies are made of a composite material, in a material gradient structure, based on metal

carbides with Co-Ni metallic binders. To obtain these bodies sintered CW materials are used withadditions of (Ta (Nb)) C, CWTiC with different proportions of metal binders of type Co, Ni and Fe.Cobalt has the role of creating an excellent connection matrix in the liquid phase through enhancedwetting properties. Nickel helps in increasing the hardness and resistance to shock of the matrix.


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Known composite materials made in the CW-Co system have the disadvantage that during thesintering heat treatment, at the eutectic temperature (1275 C), exhibit a solubility reduced carbontungsten and cobalt mass up 3.5% compared to nickel which is min. 5.4%. CW-Co sintered materialshave a higher toughness compared with Co and CW grain is


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The wear resistant body from composite material with a specific geometric shape, optimized interms of consumption of raw materials, is assembled with the connecting chain link support throughbrazing, by the method of high frequency currents, using as soldering material an Ag based alloy(Fig.9).

5. Conclusion

By studying and researching wear phenomena, this paper aims to present a novelty in the fieldby introducing objects from PM hard materials and applications of PM technology in some areasstrongly affected by wear of some parts of the excavation equipment.

References:

[1] ***, Instructions for radical repair work of the railway, no. 302, SNCFR, Railway Publishing,Bucharest, 1997;

[2] ***, Instructions for the renovation of the railway, no. 303, MTCT, CNCFCFRSA, RailwayPublishing, Bucharest, 2003;

[3] Turcanu C., Heavy railway machines, Matrix ROM Publishing, Bucharest, 2006, ISBN (10) 973-755-029-3; ISBN (13) 978-973-755-029-3;

[4] I.C. Popescu, Introduction in computer aided analysis of the process equipments, PrintechPublisher, ISBN 973- 652- 951- 7, Bucharest, 2004;

[5] I.C. Popescu, Computer aided analysis of the components of process equipments, PrintechPublisher, ISBN 973- 652- 987- 8, Bucharest, 2004;

[6] Popescu I.C., Negriu R.M., Besleaga C., Badea S.G., Stefanescu M., Case Study of the ChainExcavator, Structural Integrity and Life, Vol. 12, no. 2, page 8792, Journal of the Society forStructural Integrity and Life (DIVK) and Institute for Material Testing (IMS), Beograd, Serbia, 2012,ISSN 1451-3749;

[7] Besleaga C, Negriu R.M., Popescu I.C., Badea S.G., Stefanescu M., Applications of PM the ChainExcavator of a Railway Machine, Euro PM2011 Congress Proceedings, vol.3, pag. 427-432,Barcelona, Spain, 9-12 October 2011, ISBN 978-1-899072-22-4;

[8] Popescu I.C., Negriu R. M., Badea S. G., Besleaga Cr., Stefanescu M., Ways of deteriorating theballs with structural gradient from the valve used in the oil extraction industry, Proc. Int. Congress.,

New Trends in Fatigue and Fracture, NT2F12, Brasov, Romania, May, 2012;[9] Popescu I.C., R.M. Negriu, S.G. Badea, C. Besleaga, Case Study Regarding the Behavior of the

Structural Gradient from Various Composite Materials (WC-Co/WC-Ni), Used to Manufacture BallValves for the Oil Extraction Industry, Euro PM2012 Congress Proceedings, Basel, Switzerland,16-19 September 2012, ISBN 978-1-899072-36-1;

[10] Negriu R., Popescu I.C., Besleaga Cr., Badea S. G., Stefanescu M., Sarlea I., Balls from simplecomposites materials WC-Co and WC-Ni, with functional gradient by various concentration ofmaterials, A/00167/13.03.2012.

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Euro PM13+EP13074+Cristinel Besleaga