DE10053933B4 - Method for straightening a rail - Google Patents

Abstract

To align and straighten rails (S) to be used in a railway permanent way, after cooling at the end of hot rolling, each rail is passed through an alignment machine (R). A group of alignment rollers (1-7) act on the rail foot (F) and a group of rollers align the rail head (K). The rollers of at least one group can be set against the rail and, as the rail moves through into the first three rollers, the distortion is established by comparison of the alignment rollers in the groups until the maximum distortion is reached. As the rail advances, the other rollers are set to counter the distortion by the measured amount to correct it into a straight rail.

Description

The The invention relates to a method for straightening a rail.

Rails, produced by hot rolling or another thermoforming process usually will be based on their temperature at the end the hot deformation on a cooling bed cooled to ambient temperature. Because of the different circumstances from earth to surface at the rail head and at the rail foot longwave arise Bending. About that can out through the deformation process itself and the subsequent ones transport processes shortwave straightness deviations are caused. To similar Deformation occurs in rails, which come from the deformation heat accelerated cooled be or supplementary heat treatment be subjected.

The with such deviations from the straightness afflicted rails are as such for not to use the track construction and must therefore be directed after cooling become. The judging is usually done on a straightener, with an odd number, in particular seven or nine, straightening rollers is equipped. The odd ones (1., 3., 5., ...) Straightening rollers are generally assigned to the rail base, while the even-numbered (2nd, 4th, 6th, ...) straightening rollers on the rail head Act.

By The rolling straightening occurs at and under the running surface of the Rail head and in the middle area of the bottom of the rail foot high Tensile stresses. It has been found that these tensile residual stresses the breakage resistance of the rails with static and dynamic Reduce stress. These voltages are superimposed during operation the contact stresses caused by the rolling on the rails Wheels caused become. These contact voltages in turn solve flexural and compressive stresses out. Further tensions arise from the difference of each currently given rail temperature to the laying temperature.

Various attempts have been made to reduce the residual tensile stresses caused by roller straightening. For example, it has been proposed to apply stress relief annealing, straightening ( DE 32 23 346 A1 ), a lateral straightening ( DE 19 42 929 C ), straightening with increased railstep temperature ( DE 35 01 522 C1 ), a short-time railstalk warming ( DE 197 20 061 C2 ) or straightening with enlarged contact surfaces between the straightening rollers and the respectively directed rail ( DE 41 37 459 C2 ) to lower the residual stresses. However, none of these proposals has been implemented on a large scale. This is due, on the one hand, to the high additional costs and, on the other, to the lack of suitable technical equipment.

The maximum permissible longitudinal compressive stresses to be adhered to when rolling the underside of the rail foot have been limited to a maximum of 250 N / mm ² in EN 13 674-1 "Superstructure rails, symmetrical wide-angle rails from 46 kg / m", design September 1999. The rail head can be assumed to have corresponding values. At the same time, EN 13 674-1 limits the maximum vertical flatness deviation over a reference length of three meters to a maximum of 0.3 mm.

Of the Today's high-speed traffic makes particularly high demands to the straightness of rails and their resistance to breakage. Through a optimal straight-line condition of the rails is at low vertical and horizontal vibration excitations a quiet vehicle running guaranteed. Optimal straight running rails are therefore a prerequisite for a particularly high ride comfort and low dynamic load rail vehicles and track superstructure.

The high on the straight surface course Requirements imposed by rails make considerable bending deformations while the role of directing required. The required dimensional accuracy can be different do not reach. Such a "sharp" performed scrolling however, causes considerable residual stresses.

Also Experiments, the formation of tensile residual stresses and the processes during Role alignment in general through FEM calculations and simulation considerations have not yielded results in practice would have led to a directly exploitable improvement.

The The object of the invention is, starting from the above explained Prior art to provide a method for Rollenrichten, which without additional Facilities and means of aligning rails without the danger the emergence of high tensile residual stresses possible.

These Task is achieved by a method for straightening a rail solved, wherein the rail a Scroll straightening machine goes through, which a group of the rail foot touching roles and a group touching the rail head Has roles, wherein at least the roles of one of these groups can be adjusted in the direction of the rail, in which the employment the adjustable straightening rollers are chosen so that in the inlet area the straightening machine on a straightening roller compared with the on the other straightening rollers achieved maximum value of deformation Bending deformation is achieved, and in which those straightening rollers, the following the straightening roll, at which the maximum value of the bending deformation is reached, be traversed by the rail, so set be that the maximum bending deformation at each of these straightening rolls around each a level is reduced.

Preferably are doing those roles that go through following the straightening roll at which the maximum value of the bending deformation is reached is traversed by the rail, so employed that the amplitude the bending deformation at each of these roles degressive with possible high degression is reduced. As a result, the emergence of Residual tensions are particularly effectively avoided. Cheap is it in this regard about it addition, if the rollers following the roller with the highest bending deformation be run through positioned roles, so hired, that the Rail in the transition area the elastic-plastic alternating bending is converted into the straight state.

A targeted distribution of already present at a low level Residual stresses over the Cross-section of the directed rail can be achieved by that starting from an initial setting the employment of the in the discharge area positioned rolls of straightening machine on the ratio of bending curvatures is varied at the respective roles of about 0.7 to 1.3.

According to the invention becomes during the straightening process by employment of a straightening roll causing a maximum bending deformation on a roll with the rail foot in contact is. This deformation is sufficient to achieve the desired straightening effect. The constant caused by this maximum bending deformation curvature the rail is on the subsequently passed straightening rollers by alternating bending of the rail with gradually decreasing amplitude reduced.

Surprised has been shown on This way a rail can be straightened which is an optimal one Straightness at low tensile residual stresses. consuming Aftertreatments of the invention directed rail needs not for that.

Especially good results of straightening while minimizing tensile residual stresses can be achieved when the Biegerichtrolle, at which the maximum bending deformation is achieved assigned to the rail is. It is also cheap if the gradation of the individual Verfomungsschritte in the dismantling of maximum bending deformation is designed so that the Biegerichtrolle on the the last plastic deformation of the rail during gradual dismantling the maximum bending deformation is achieved, also assigned to the rail foot is. It has been shown that in particular in such a distribution of the gradual "Rückverfomung" of the rail, a minimum of tensile residual stresses can achieve at the same time optimized straightness.

The inventive method let yourself in an excellent way to conventional built straightening machines perform where the straightening rollers the first group in the conveying direction the rail is offset from the rollers of the second group are. The staggered arrangement is commonly referred to as pitch. In practice, it is common Rail leveling machines with pitches of 1400 - 1800 mm. The division The rolls can be equal to a straightening machine, different sizes or variable be adjustable. The roles can in the machine horizontally over each other or be arranged vertically next to each other.

Conventional straightening machines are equipped with adjustable head rollers or with adjustable castors. The necessary for the straightening process alternately changing bends are achieved in the so-called Richtdreiecken. In known straightening machines of the type in question each form two straightening rollers of a group with a straightening roller of the other group such a directional triangle. With regard the invention is favorable in this context, when the straightening roller on which the highest bending deformation is achieved, the last passed straightening roller of a straightening triangle. It is also favorable if the relevant directional triangle, to which the straightening roller is assigned, at which the highest bending deformation is achieved, is arranged at the beginning of the straightening track through which the rail passes. In this way, the gradual reduction of the highest bending deformation can be done safely even on machines with a low number of rolls. Thus, the method according to the invention can be carried out, for example, on straightening machines, which are equipped in a known manner with seven or more straightening rollers. It is favorable in terms of the desired minimization of residual tensile stresses when the respective odd-numbered straightening rollers are assigned to the rail.

following the invention is based on a two embodiments performing Drawing closer explained. They show schematically:

1 a section of a horizontal straightening machine in a plan view;

2 a section of a standing straightening machine in lateral view.

In the 1 illustrated, constructed in a conventional manner straightening machine R is with at least seven straightening rollers 1 to 7 fitted.

In the leveler R is a rail S directed previously through Hot rolling produced and on a cooling bed, not shown the approx. 900 ° C having been cooled to room temperature is.

The odd-numbered straightening rollers 1 . 3 . 5 and 7 the straightening machine R are assigned to the rail foot F of the rail S, while the even-numbered, vertically adjustable straightening rollers 2 . 4 . 6 act on the rail head K. The rail head K associated straightening rollers 2 . 4 . 6 are in the conveying direction P of the rail S offset in relation to the rail F associated straightening rollers 1 . 3 . 5 . 7 arranged that each one of the straightening rollers 2 . 4 . 6 in relation to the horizontal, in each case in the middle between a pair of straightening rollers 1 . 3 . 5 and 7 is arranged. In this way, the straightening rollers form 1 . 2 and 3 the vertices of a first directional triangle RD1. A second directional triangle RD2 is through the straightening rollers 2 . 3 and 4 formed, a third directional triangle RD3 through the straightening rollers 3 . 4 . 5 etc. The straightening triangles RD1 to RD3 are in 1 indicated by dashed lines. Between each of a directional triangle RD1, RD2, RD3, ... associated straightening rollers 1 to 7 the rail S is bending deformed in an alternating direction.

The rail head K associated straightening roller 2 is employed in the vertical direction on the rail foot F, that the rail S when passing the straightening roller 3 undergoes a maximum bending deformation. Starting with the then passed straightening roll 4 the resulting continuous curvature of the rail S is gradually reduced. The gradation is chosen so that the last still as plastic to be designated bending deformation at the rail F associated straightening roller 5 he follows.

The during execution Bending curvatures required in the straightening process are as follows Table 1 for two examples given. Example 1A refers to a Rail with normal or small curvature differences after the Cooling, while Example 1B for a rail with larger curvature differences applies.

Table 1

In this context, a curvature is defined as positive if the bending takes place on a roller over the rail head K, ie on the rollers 2 . 4 and 6 , As negative, the curvatures are defined when the bending takes place via the rail foot F, ie on the rollers 3 and 5 ,

In practical tests on rails of the profile UIC60 in grade UIC900A has been found that on a according 1 trained straightening machine according to the inventive method after straightening the Längszugspannungen in the rail head K are compared with the adjusting conventional approach Längszugspannungen reduced by more than half.

In the 2 Straightener shown is with nine rollers 11 to 19 equipped, in contrast to the example according to 1 not the even-numbered rollers associated with the rail head K. 12 . 14 . 16 . 18 but the odd-numbered roles associated with the rail foot F. 11 . 13 . 15 . 17 . 19 are mounted adjustable in the vertical direction. The larger number of straightening rollers 11 to 19 has the advantage that by means of suitable employment of roles 11 . 13 and 15 maximum curvature of the rail S to the roll 15 can be attributed very quickly to a low curvature value, so that on the rollers 16 . 17 and 18 only has to be addressed with a small amplitude of curvature.

Table 2 gives an example of when straightening a rail S in the in 2 illustrated straightening machine applied to the individual straightening rolls related bending curvatures k * / v. Based on such an adjustment of the straightening machine, it is possible by targeted variation of the employment of arranged in the directional range of the machine rollers 15 . 17 and 19 adjust the residual stress distribution in the directional rail according to the practical requirements. The grading of the roles with this objective changed 16 and 17 each impressed curvatures is set in parentheses in the associated rows of Table 2.

Table 2

In the same way as in Table 1, in Table 2, a curvature is defined as positive when bending takes place on a roll via the rail head K, ie on the rolls 12 . 14 . 16 and 18 , As negative, the curvatures are defined when the bending takes place via the rail foot F, ie on the rollers 13 . 15 and 17 ,

The "related bending curvatures" mentioned in Tables 1 and 2 correspond to the bending curvatures k _v in the contact area of the rollers 1 to 7 respectively. 11 to 19 , which are related to the maximum possible elastic bending curvature k _{s of} the rail S, where k _s = 2 * R _p0.2 / E * h. With R _p0.2 the 0.2% test limit or the yield strength of the rail steel to be straightened, E is the modulus of elasticity and h is the height of the profile of the respective rail S. This results in k * / v = k _v / k _s .

at those listed in Tables 1 and 2 above Gradations are guidelines, which are the orders of magnitude in which the steps passed after the highest bending deformation the "reversion" lie. In practice For example, the maximum bending deformation and the stages of the subsequent "re-deformation" become substantially proportional to the yield strength and the hardening behavior of the Dimensioned rail material. The value of the highest Biegeverfomung must be greater the bigger the after cooling the rail S curvatures existing and ripples of the rail S are.

If the values of the maximum bending deformation and the last still effective plastic deformation are determined, the necessary adjustments can be made between the straightening roller 3 respectively. 13 where the highest bending strain is generated and the straightening roll 5 respectively. 16 or 17 where the last plastic Ver formation of the rail S can be determined by considering the elastic plastic bending of the rail S. The influencing factors are the technical data of the leveler R (pitch, diameter, number, type of setting of the straightening rollers, deformation of the straightening machine R as a result of the straightening process).

Of course you can the straightening of the rail S can also be performed on leveling machines, which are equipped with more than nine rolls. It turns out that on such Machines achieved a further reduction in tensile residual stresses can be.

Practical tests on rails of the profile UIC60 in grade UIC900A have shown that on a according 2 trained straightening machine in the inventive approach after straightening the Längszugspannungen over the adjusting themselves in the usual procedure longitudinal tensile stresses are reduced by 40 on average.

1-7

straightening rollers

11-19

straightening rollers

F

Rail foot of the rail S

K

railhead the rail S

P

conveying direction the rail S

R

straightener

RD1, RD2, RD3

Directional triangles

S

rail

Claims (11)

Method for straightening a rail (S), - in which the rail (S) passes through a roller straightening machine (R), which has a group of rollers contacting the rail foot (F) ( 1 . 3 . 5 . 7 ; 11 . 13 . 15 . 17 . 19 ) and a group of the rail head (K) touching rollers ( 2 . 4 . 6 ; 12 . 14 . 16 . 18 ), wherein at least the rollers ( 1 to 7 ; 11 to 19 ) one of these groups in the direction of the rail (S) are adjustable, - in which the employment of the adjustable straightening rollers ( 2 . 4 . 6 ; 11 . 13 . 15 . 17 . 19 ) is selected so that in the inlet region of the straightening machine to a straightening roller ( 3 ; 13 ) compared to the other straightening rollers ( 1 . 2 . 4 . 5 . 6 . 7 ; 11 . 12 . 14 to 19 ) deformations achieved maximum value of the bending deformation is achieved, and - in which those straightening rollers ( 4 . 5 . 6 . 7 ; 14 to 19 ) following the straightening roller ( 3 ; 13 ), at which the maximum value of the bending deformation is reached, are traversed by the rail (S), adjusted so that the maximum bending deformation at each of these straightening rollers ( 4 . 5 . 6 . 7 ; 14 to 19 ) is reduced by one level. Method according to claim 1, characterized in that those rollers ( 4 . 5 ; 14 . 15 ) following the straightening roller ( 3 ; 13 ), at which the maximum value of the bending deformation is achieved, are run through by the rail (S), so employed that the amplitude of the bending deformation at each of these rollers is degressively reduced with as high a degression as possible. Method according to Claim 2, characterized in that the rollers ( 6 . 7 . 8th . 9 ; 16 . 17 . 18 . 19 ), which after the following ( 3 ; 13 ) rollers with the highest bending strain ( 4 . 5 ; 14 . 15 ) are performed, so employed that the rails (S) are transferred in the transition region of the elastic-plastic alternating bending in the straight state. Method according to one of the preceding claims, characterized in that, starting from an initial setting, the employment of the rollers positioned in the outlet region ( 5 . 7 ; 15 . 17 . 19 ) of the leveler over the ratio of the bending curvatures on the respective rollers ( 5 . 7 respectively. 15 . 17 . 19 ) is varied from about 0.7 to 1.3. Method according to one of the preceding claims, characterized in that the bending roller ( 3 ), at which the maximum bending deformation is achieved, the rail foot (F) is assigned. Method according to one of the preceding claims, characterized characterized in that Biegerichtrolle, at the last plastic deformation of the rail (S) achieved in the gradual reduction of the maximum bending deformation is assigned to the rail head (K). Method according to one of the preceding claims, characterized in that the straightening rollers ( 1 . 3 . 5 . 7 ; 11 . 13 . 15 . 17 . 19 ) of the first group in the conveying direction (P) of the rail (S) offset to the rollers ( 2 . 4 . 6 ; 12 . 14 . 16 . 18 ) of the second group are arranged. Method according to claim 7, characterized in that in each case two straightening rollers ( 1 . 3 . 5 . 7 ; 11 . 13 . 15 . 17 . 19 ) of a group with a straightening roll ( 2 . 4 . 6 ; 12 . 14 . 16 . 18 ) of the other group form a directional triangle (RD1, RD2, RD3) and that the straightening roller ( 3 ; 13 ), at which the highest bending deformation is achieved, the last passing straightening roller ( 3 ; 13 ) of a straightening triangle (RD1). Method according to claim 8, characterized in that the directional triangle (RD1) to which the straightening roller (RD1) 3 ; 13 ) is assigned, at which the highest bending deformation is achieved, is arranged at the beginning of the by the rail (S) traversed straightening. Method according to one of the preceding claims, characterized in that, the leveler (R) at least seven straightening rollers (R) ( 1 to 7 ), preferably nine straightening rollers ( 11 to 19 ). Method according to claim 10, characterized in that the respective odd-numbered straightening rollers ( 1 . 3 . 5 . 7 ; 11 . 13 . 15 . 17 . 19 ) are assigned to the rail foot (F).