U.P.B. Sci. Bull., Series …, Vol. …, Iss. …, 201.. ISSN 1454-2331

STUDY CASE OF A TAMPING TOOL WITH CAD METHOD

Sorin George BADEA1, Ionel POPESCU2, Cristinel BESLEAGA3, Constantin MINCIU4

Sculele de burare se utilizeaza la operatiile tehnologice de burare, care sunt incluse in procesele tehnologice de constructie si reparatie a caii ferate. Aceste scule sunt solicitate la solicitari compuse de incovoiere, compresiune, soc, vibratii, oboseala, uzura abraziva etc. Studiul si cercetarile privind aceste scule solicita un mare consum de timp, resurse materiale si financiare. In aceasta lucrare este propusa o metoda de studiu, privind o scula de burare tip BNRI-85 model 2007 utilizand CAD. Rezultatele teoretice sunt comparate cu cele experimentale, care au fost obtinute in conditii reale, de santier.

Tamping tools are used at the tamping technological operations, which are included in the technological process by building and maintenance of the railway. These tools are stressed at compounds stress by bending, compression, shock, oscillations, fatigue, abrasive wear and s.o. The study and researches to these tools request a lot of time, materials and financials resources. In this paper is proposed a study method regarding to a tamping tool type BNRI- 85 model 2007 using CAD method. The theoretical results are compared with experimental results, which have been obtained/ achievement in real conditions, in situ.

Keywords: tamping tool, stress evaluation, lastingness, CAD method, defects.

1. Introduction

Tamping tools are the most stress elements from a tamping machine compound. These tools are stressed to bending, compression, shock, oscillation, fatigue, abrasive wear and so another. By the good behavior of these depend: the quality of the tamping operation, the stability/ the lastingness of the geometry of the railway, the size of costs of tamping operation and of course, the costs for building and maintenance of the railway [1].

Tamping tools are made, in generally, by each tamping machine producer, especially for each type of tamping machine. The technical details of these tamping tools are few or are missing. It is unknown or is known a little, about the 11 Engineer, Manager SC IMCF SA Bucharest, Romania, e-mail: soringeorgebadea@yahoo.com2 Lector doctor engineer, Process Equipment Department, Faculty of Mechanic and Mechatronic, University “Polytechnic” from Bucharest, Romania, e- mail: ic.popescu@yahoo.com 3 Doctor engineer, Chief of SIMC Buzau – SC IMCF SA Bucharest, Romania, e-mail: cristibesleaga@yahoo.com 4 Professor doctor engineer, Machines and Systems of Production Department, Faculty of IMST, University “Polytechnic” from Bucharest, Romania

Sorin George Badea, Ionel Popescu, Cristinel Besleaga, Constantin Minciu

behavior of the tamping tools in using, about technological process by manufacturing, the weariness and the wear process during using of these, about the stress system and his effects [2, 3, 4, 5, and 6]. The producers of tamping tools offer/ give, especially, details regarding to the marketing and commercial elements.

By a little time, its have been started and presented, researches and studies concerning to tamping tool, type BNRI- 85 model 94 (1994), using CAD method, through finite elements [7]. The difficulties in these researches and studies are: many type of tamping tools, with different dimensions, size, shape, materials, technological processes for manufacturing; the different stress systems for tamping tools, depending by using conditions: type of tamping operations, the hardness of the prism of ballast, the lifting size in leveling operation, the work regimen of the tamping machine; the finding and definition of hypotheses/ assumptions, for maximum stresses and so another [8].

This paper have as a main objectives, researches and study a new tamping tool, type BNRI- 85, model 2007, which has been designed in 2007 and now, it is in experimental study and researches. Tamping tool type BNRI- 85, model 2007, has a few different important constructive elements, like the shape of axe, which is right, the position of the tine against/ towards the axe and sizes, which bring more technological advantages, comparative with the tamping tool type BNRI- 85, model 94 (1994). We have made the researches and study using CAD method and we have compared the results with experimental results.

2. Tamping tool type BNRI- 85, model 2007

Tamping machine type BNRI- 85 (Fig.1), for which has been designed this new tamping tool, type BNRI- 85, model 2007 (Fig.2), has a large spreading/ extent, in big numbers (more than 60) at Romanian Railways.

Fig.1. Tamping machine type BNRI- 85

Study case of a tamping tool with CAD method

Fig.2. Tamping tool type BNRI- 85, model 2007

The material for the body and tine of tamping tool is 42MoC11, STAS 791- 86, σr (Rm) =740÷ 1270 [N/mm²], σ0,2(Rp0,2) = 510÷ 880 [N/mm²], σ-1 = 483 [N/mm²], A5 = min.10, KCU 300/5= 39 [J/cm²] ([kgfm/ cm²]), KCU 300/2= 39 [J/cm²] ([kgfm/ cm²]), Brinell hardness= max.217 [HB].

The materials for covering the tine, for increasing the resistance at the wear process, especially at the abrasive wear and shock, are those which are deposed through manual electrical welding, with covering metallic electrodes, using two types’ electrodes: first electrode, utilized like a intermediary/ buffer’ material, between main material and final hard material, is BOHLER FOX A 7,

Sorin George Badea, Ionel Popescu, Cristinel Besleaga, Constantin Minciu

DIN 8555: E8-200; DIN 8556: EKb 18.8. Mn 6 20 +, having as main chemical’ elements: C=0,15%; Mn=6%; Si=1,1%; Cr=19%; Ni=8,5% ; the second (final) electrode, utilized like final layer, is FOX LEDURIT 60, DIN 8555: E 10– 60, having as main chemical’ elements: C=3,4%; Mn=0,2%; Si=1%; Cr=33%.

3. Designing of tamping tool type BNRI- 85, model 2007, with CAD

For to theoretical study case of the tamping tool BNRI- 85, model 2007 (Fig.2), were used two CAD soft (AutoDesk Inventor Professional 2008 and ANSYS Workbench, rev. 11), in collaboration with the Thermal Research Center, in the Faculty of Mechanical Engineering and Mechatronics of the Polytechnic University in Bucharest [9, 10]. There are used 301725 nods and 199727 elements.

The model has been designed with the help of the digital prototyping is presented in Fig. 3.

Fig.3. The model of tamping tool type BNRI – 85, model 2007

4. Establishing the mains owns frequencies for tamping tool type BNRI- 85, model 2007, with CAD

In Fig.4 is presented the discretization in finite elements.The mains own vibrations frequencies, for tamping tool BNRI – 85 model

2007, have been established and presented below (Fig.5, 6, 7), using CAD methods, which are based on finite element. In this way, we give an answer regarding to the question, if the own vibrations frequencies are overlaps on the work’ frequency by 35 [Hz].

Study case of a tamping tool with CAD method

Fig.4. The discretization for tamping tool type BNRI- 85 model 2007

Fig.5. The first own frequency by 303.92 [Hz]. Fig.6. The second own frequency by 314.04 [Hz]

The other owns frequencies aren’t important, because their values are bigger than the work’ frequency by 35 [Hz]. We have established that, it isn’t the risk by occurring of the resonance phenomenon.

5. The analysis of the induced stress for 3D model with CAD

Simulation of the induced stresses and deformations, by modeling the tamping tool/ pick BNRI – 85, model 2007, with finite elements, was carried out by taking into consideration of the following assumptions [11, 12, 13, 14 and 15]:

Sorin George Badea, Ionel Popescu, Cristinel Besleaga, Constantin Minciu

- the body and tine of tamping tool are made from a metallic material, homogeneous and isotropic;- modeling of 3D body has been made as close to the model of the designing tamping tool; some connection rays, which have been selected in a suitable manner for the discretization of the finite elements, did not lead to notable values of the stress and deformation conditions;- there have not been taken into account the options of the computing program connected to high, as well as elastic- plastic deformations;- stresses and forces which occur during the tamping operation, both in the vertical motion, by penetrating of the crushed stone from the component of metal ballast prism, by the tamping tool and during the simultaneous motions, on the horizontal direction, by vibration and compression of the crushed stone executed by the tamping tool, are not applied by shock (with high speed and small shifts during the application of the stress/ force) and, when reaching the maximum value of the stress/ force applied, the crushed stone starts cracking and the stones will move, while the tine will move in the environment considered as uniform and homogeneous;- during the stress on the horizontal direction, at the simultaneous vibrating and compressing motion of the crushed stone by the tamping tool, the reaction value due to the crushed stone decreases in time, according to its breaking up/ fluidization;- it wasn’t taken in the analysis the situation, in which, force should also be applied on the other side of the tamping tool (secondary, rear side of the tine) due to the following reasons: the secondary side is inclined with a large relief angle, making the forces/ stresses that appear on this surface to break down and to reduce their value and effect; until now, there haven’t been identified major/ predominant factors regarding the stresses, deformations, durability and so another, that affect the secondary side; in case of tamping tools executed through non-dismountable assembling by welding, between the body and cam follower, there haven’t been damages/ faults as a consequence of forcing the welded joint between the body and cam follower, stresses due to forces acting on the secondary side;- the value of the reaction, which arises because of these two extreme situations, in which can be found the prism of crushed stone, due to the different rate of wear/ clogging (i-the new or clean ballast prism met at the construction, capital repair, periodical maintenance with the total riddling of the ballast prism; ii- the operating ballast prism, with different rates of clogging);- the stones are free and they can move freely; there is only point or surface contact;

Study case of a tamping tool with CAD method

- the stones are linked together with material (resulted from wear, break, grind of crushed stone, from bad weather, drained material, fallen from the rolling stock and so another) which after strengthening, it could get various consistencies;- for the calculation at weariness, Gerber correction of the medium tension was used.

The discretization model of tamping tool BNRI- 85, model 2007 is presented in Fig.8.

Fig.8. The discretization’ model of tamping tool type BNRI- 85-2007

For modeling of the solicitations’ system, we have taken into account the most disadvantages situations. The material which will be worked, the crushed stone- the ballast, which contain many stones, can take contact with the surface of the active part of tamping tool- tine, in one point or simultaneously, in many point. This is an aleatory situation. The most disadvantage situation of solicitation is, if the contact, between surface of tine and crushed stone is made in one point.

We have analyzed three cases, on which we have considered the most disadvantages solicitations. These three cases are presented below.

5.1. The analysis of the induced stress for 3D model with CAD- case 1

The directions and the applications points of the horizontal and vertical forces, for case 1, are presented in Fig.9.

Sorin George Badea, Ionel Popescu, Cristinel Besleaga, Constantin Minciu

The equivalent stresses (tensions) are presented in Fig.10.

Fig.9. Case 1- The system of solicitations for tamping tool BNRI-85, model 2007

Fig.10. The equivalent stresses (tensions), for case 1 by system of solicitations

Study case of a tamping tool with CAD method

5.2. The analysis of the induced stress for 3D model with CAD- case 2

The directions and the applications points of the horizontal and vertical forces, for case 1, are presented in Fig.11.

The equivalent stresses (tensions) are presented in Fig.12.

Fig.11. Case 2- The system of solicitations for tamping tool BNRI-85, model 2007

Fig.12. The equivalent stresses (tensions), for case 2 by system of solicitations

Sorin George Badea, Ionel Popescu, Cristinel Besleaga, Constantin Minciu

5.3. The analysis of the induced stress for 3D model with CAD- case 3

The directions and the applications points of the horizontal and vertical forces, for case 1, are presented in Fig.13. The equivalent stresses (tensions) are presented in Fig.14 and Fig.15.

Fig.13. Case 3- The system of solicitations, Fig.14. The equivalent stresses (tensions), for tamping tool BNRI-85, model 2007 for case 3 by system of solicitations

Fig.15. The equivalent stresses (tensions), for case 3 by system of solicitations

Study case of a tamping tool with CAD method

6. The experimental results

During the experimental researches of the tamping tool BNRI- 85, we have achieved some defects (damages), at the bodies and the tines (the active part). A few defects are present in Fig.16. In this way, we can make a comparison, between those three cases analyzed through CAD method and the experimental results.

Fig.16. Defects (damages) at the BNRI- 85 tamping tool, at the body and the tine (active part)

7. Conclusions

- Designing a tamping tool and checking of this, to the different stress, with especially CAD soft, can offer many advantages, possibilities and reduce a lot of time and more accurate results;- Another novelty is represented by the determination of owns vibrations frequencies of a tamping tool (BNRI – 85, model 2007), using computer- aided modern methods- CAD, methods which are based on finite element. From the analysis performed, after establishing the 2 own frequencies ( ) of the tamping tool BNRI – 85 type, model 2007, it can be concluded that the operating frequency f = 35 Hz is not found in any of the ranges 0.8 ÷ 1.2 from the values of those six own frequencies and, therefore, there is no danger of occurrence of the resonance phenomenon.- Modeling of the stress state from tamping tool using finite elements method has leaded to following conclusions:

- The stresses from the body of tamping tool are at the acceptable level; thus, don’t appear the possibility a damages at a little numbers by cycles; for some of them can appear the breakage (Fig.10, 12 and 16)

- In the zone where is applied the force (the contact between a stone and the plane surface of tine) the stresses are bigger than break’ limit and in that zone will appear the defects (damages) of material. Because the material of the crushed stones is very hard, and it has many points/ vertexes, this fact can lead to the cutting of the surfaces and to the wear of the surfaces (Fig. 10, 12, 15 and 16).

Sorin George Badea, Ionel Popescu, Cristinel Besleaga, Constantin Minciu

References:

[1] Cr. Besleaga, Contributii privind marirea durabilitatii sculelor de burare (Contributions regarding to increase the lastingness of the tamping tools), Doctorate thesis, 625.144.5(043-2876) B-UP 1, Bucharest, (2006).[2] Turcanu Constantin, Masini de constructii pentru caii de comunicatii, Masini de constructii pentru cai ferate, Institutul de constructii Bucuresti, 1982[3] Turcanu Constantin, Masini de cale (Railway machines), Editura MATRIX ROM, Bucuresti, 2006, ISBN (10) 973- 755- 029- 3; ISBN (13) 978- 973- 755- 029- 3[4] ***, Instructiuni privind executarea lucrarilor de buraj, ridicarea caii la nivel longitudinal si transversal si riparea caii cu masinile grele de cale de tip BNRI sau BMNRI (Instructions regarding to execution of tamping, lifting of railway to the longitudinal and transversal level and lining of railway with heavy railway machines type BNRI or BMNRI) nr.465/277-1973, Departamentul cailor ferate/Directia Linii si Instalatii, Bucuresti 1980[5] ***Plasser&Theurer, Pickel long: CU 30.4320, Plasser&Theurer Austria, 1995[6] ***Plasser&Theurer, Stopfpickel service vorschrift, ein-u. Ausbau, Regenerierung; S19-01; Plasser&Theurer, Austria, 1994[7] Cr. Besleaga, I.C. Popescu, R.M. Negriu, S.G. Badea, Study case- tamping tools with the reinforcement by tungsten carbide at the tine, TEHNOLOGIA INOVATIVA, REVISTA CONSTRUCTIA DE MASINI, serie noua, anul 61/2009 – nr. 2-3, pag. 5÷ 10, Editura OID – SC ICTCM SA, Bucuresti 2009, ISSN 0573-7419 [8] S.G. Badea, Cercetari experimentale privind durabilitatea sculelor de burare, Referat nr. 2, Cap. 6.3., pag. 100÷ 122, Teza de doctorat: Cercetari privind studiul comparativ al durabilitatii sculelor de burare, Catedra Masini si Sisteme de Productie, Facultatea Ingineria si Managementul Sistemelor Tehnologice, Universitatea Politehnica din Bucuresti, Bucuresti, 2009 [9] I.C. Popescu, Introduction in computer aided analysis of the process equipments, Printech Publisher, ISBN 973- 652- 951- 7, Bucharest, (2004)[10] I.C. Popescu, T. Prisecaru, B. Finite elements Analysis of Pressure Equipment, Computer Aided Engineering Solutions for Design, Analysis and Innovation, (ANSYS & FLUENT User Group Meeting), 26-27 Aprilie 2007, Sinaia [11] P. Georgeoni, N. Arnici, I.C. Popescu, and s.a., Using the isostatical pressing at the manufacturing of big machine parts by high performances from sintered metallic carbides, Metallurgical Researches, ICEM, Vol.26, page. 463 - 475, 1985, Bucharest.[12] P. Georgeoni, I.C. Popescu, Considerations regarding to manufacturing of machine parts from metallic carbides type WC-Co with A.I.P. destination, Metallurgical Researches, ICEM, Vol.26, page. 477 - 483, 1985, Bucharest. [13] V.V.Jinescu, I.C. Popescu, Reactors by very high pressure with the elements manufactured from the tungsten carbides and cobalt, Chemistry Review, nr. 12, 1997, page. 981 - 991, ISSN 0034-7752, (ISI-MJL 7569);[14] V.V.Jinescu, I.C. Popescu, Reactors by very high pressure with the elements manufactured from the tungsten carbides and cobalt, II, Chemistry Review, nr. 1, 1998, page. 56 - 63, ISSN 0034-7752, (ISI-MJL 7569);[15] P. Georgeoni, I.C. Popescu, M. Istrătescu, L. Argeşanu, The behavior of different types hardness alloys from WC – Co system, used at manufacturing of dies for reactors by very high pressure, Mechanical Breakage, nr. 9, page. 8 - 14, 2000, ISSN 1453-8148.