Defect formation problems

in wheel-rail steam

 

A.    G. Petrakova

Omsk State University of Railway Communication, 35 pr. Marksa, Omsk, 644046, Russia

E-mail: petra-anna@yandex.ru

 

ABSTRACT

This work presents the reasons of the freight cars wheels and rails defect formation. The main ways of decreasing defect formation are presented in the article as well.

 

Keywords: Wheel, rail, defect formation, optimization, wear resistance

 

1. Introduction

The major priorities for JSC RZhD is the perspective train-passing development at the guaranteed traffic safety and the increasing of overall performance on the basis of track maintenance and rolling stock interaction. For its realization it is necessary [1]:

- to provide notable increase of weight and speed of train movement,

- increase in running and axial loading of a rolling stock,

- to pass to the models of driving that are most favorable from the point of view of the energy saving,

- to reduce the material and power losses connected with wear of wheel rail system friction.

These problems are considered to be the main in rolling stock service.

One of the consequences of increasing in axial loadings is inability of wheels and the rails made of steel of traditional brands, to correspond to new quality standards. The operation resource and reliability of rubbing wheel rail pair in most cases are defined by a condition of driving of a wheel and a rail head. The traffic safety of a rolling stock depends on these defects of the surface.

 

2. Main defects and reasons

For the railroads working in the conditions of heavy movement when axial loading is in limits of 23,5 — 30 t, interaction problems now are [2, 6, 8, 10]:

• contact fatigue damages of wheels and rails, including thermomechanical damages;

• formation of wheel roll in form of a through wave;

• plastic deformation of wheel and rail working surfaces;

• splitting off of a wheel rim;

• descents because of a wheel wave on a rail;

• break of a rail and destruction of rails in a zone of a welded joint.

Wear and damage reduce resistance of detail fatigue and can be the reason of their destruction even at insignificant concentrators of tension and very low rated voltage [3].

Researches wheel and rail surface damages of different types and nature of destruction give the grounds to claim that destructions are a consequence of a large number of the reasons which generally depend on physicomechanical properties, violations in manufacturing techniques and repair, a tension in a place of destruction and dynamic loadings.

 

3. Ways of decreasing defect formation

Having defined the main reasons for defect formation in wheel rail steam it is possible to allocate the following perspective ways of decrease:

- the design

They are directed on constructive changes in wheel rail steam,

- the all-technical

They are directed on development of additional stages of production, operation and repair quality control.

- the technological

They are connected with modification of technological process of production or repair.

In the design direction three main ways of decrease in defect formation in wheel rail steam are allocated: the reduction of relative slipping, the tension reduction in a contact zone, the improvement of a technical condition of brake system.

For the management of wheel and the rails blanket properties are providing good contact in a wheel rail steam, and the reduction of relative slipping the introduction of «the third body» is carried out (Lubrication for wheel wave contact zone with lateral surface of a rail head and use of friction activators for coupling of locomotives in a draft mode increase).

Decrease in tension in a zone contact "wheel rail" is the difficult task connected with determination of the sizes of a spot of the contact and contact tension. At reduction of the area of a spot of the contact the size of contact tension starts growing, surpassing a limit of fluidity of wheel steel. With increase in loading at a wheel this process amplifies, besides separate sites are excessively overloaded that leads to formation of superheated zones and undesirable consequences. If the overheat reaches recrystallization temperature, the decrease of hardness of such site is inevitable.

The size and distribution of contact tension significantly depend on wheel and rail profiles and on what contact takes place. But at the solution of this task optimization of a seamless-rolled wheels profile combined with operational profiles of rails is necessary. However the profile has been changed only once towards the reduction of thickness of a wheel crest [5].

One more design measure is decrease of defects of a brake origin in quantity. For this purpose it is necessary to carry out the improvement of a brake system technical condition, the improvement of a material and a design of blocks, the mechanization of hump yards [7, 9].

All-technical actions include quality control of repair and production modern diagnostics of a driving surface condition of wheels, introduction of devices finding wheel defects and also development of a way to recognize the size of defects at their diagnosing [4].

The complex of technological measures has to be directed on improvement of wheel repairing (economic turning of wheel couples and increase of its quality, creation of informational system for the analysis of defects, time and the reasons of wheel couple turning), and also on increase of material firmness of a wheel to defect formation. The most perspective at this stage is hardening of a driving surface of a wheel.

 

4. Conclusion

Until recently JSC RZhD management most often tried to eliminate harmful consequences of high axial loadings at the expense of improvement of the equipment by greasing of working surfaces of wheels and rails, and also using high-strength steel at production of wheels [9, 11]. These measures though reduced rate of wear, but increased quantity of other defects on working surfaces both wheels and rails. The integrated approach, carrying out scientific researches and considerable investments is necessary for decreasing defect formation in wheel rail steam.

 

REFERENCES

1. Lysyuk V. S. The reasons and the mechanism of a descent of a wheel from a rail. Problem of wear of wheels and rails. — M: Transport. — 2002.

2. Buynosov A. P. Wear of bandages and rails: reasons and possibilities of reduction//Railway transport. — 1994, No. 10, 39 — 41.

3. Sosnovsky L.A., From V.I. Problem pair of wheels and rails with position Tribo-Fatigue// Railway transport. — 2007, No. 1, 38 — 44.

4. Bogdanov A. F., Chursin V. Operation and repair car wheel pairs. M., "Transport" - 1985.

5. Creating optimal railway wheel profile. -URL: http://pr.adcontext.net/42/07/11/19/6919. (date of access: 10.02.2012).

6. Mitrokhin A. N. Report "wheel - rail": unresolved issues. "Road and track facilities", 2007, ¹ 12.

7. Moroz B. A., Marutina K. A., Balanovsky A. E. The complex system of resource wheels and rails (the experience of the East-Siberian railway)// Locomotive, 1998, ¹ 19, p. 19-22.

8. Balanovsky A. E, Hayashi S. The problem of wear of the friction pair wheel-rail (brief analysis and proposals). - Irkutsk: Plazmoprotek, 1997, 56 p.

9. Bogdanov, V. Markov, D. P, Penkova T. I. Optimization of the tribological characteristics of rolling wheel flange// Bulletin VNIIZhT, 1998, ¹ 4, p. 3-9.

10. Neglinsky V. V. Generalization of the results of operational observations wear flanges locomotive wheelsets // Friction and Wear, 1995, ¹ 1, p. 119-125.

11. Petrakova A. G. Optimization hardness rolled wheel wagon// Friction and Wear, 2009, ¹ 1, p. 42-46.