EP1201329A2 - Method and roll straightening device for straightening rails - 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 invention relates to a method for straightening Rails.

Rails made by hot rolling or another Thermoforming processes are usually produced based on their temperature at the end of hot forming cooled to ambient temperature on a cooling bed. Because of the different ratios of mass to Surface on the rail head and on the rail base arise thereby long-wave bends. In addition, you can through the deformation process itself and the subsequent ones Short-wave transport processes Straightness deviations are caused. To similar ones Shape errors occur with rails coming from the Deformation heat can be cooled or accelerated be subjected to additional heat treatment.

Those with such deviations from straightness Affected rails are as such for track construction not usable and must therefore after cooling be judged. Straightening usually takes place on a straightener with an odd number, especially seven or nine, straightening roles is. The odd-numbered (1st, 3rd, 5th, ...) Straightening rollers are generally the rail foot assigned, while the even numbers (2nd, 4th, 6th, ...) Straightening rollers act on the rail head.

The roll straightening creates on and under the Driving surface of the rail head and in the middle of the Bottom of the rail foot high tensile residual stresses. It it has been found that these tensile residual stresses Break resistance of the rails with static and reduce dynamic stress. These tensions the contact voltages are still superimposed during operation, by the wheels rolling on the rails caused. These contact tensions in turn release Bending tensile and compressive stresses. More tensions arise from the difference of each current given rail temperature to the bracing temperature.

Various attempts have been made by the roll straightening caused tensile residual stresses reduce. For example, a Stress relieving, stretching (DE-A 32 23 346) lateral straightening (DE-C 19 42 929), a straightening with increased rail web temperature (DE-C 35 01 522), a short-term rail bar heating (DE-C 197 20 061) or straightening with increased contact areas between the Straightening rollers and the respective directed rail perform (DE-C 41 37 459) to the residual stresses decrease. On an industrial scale, however, has prevailed none of these suggestions. On the one hand, this is due to the high additional costs and secondly due to the lack appropriate technical facilities.

In addition, DE-A 36 05 648 is a method and a device for straightening railroad tracks remove. The tenor here is that the rail during as they pass through the machine changing bends are imprinted in the so-called directional triangles, and so that the rail when straightening one overall curved trajectory with the center of curvature takes place below the rail foot. As a result, the rail runs through the straightening machine from one to the other Spout in an arc over the rail foot - overlaid of the mutual bends in the individual Directional triangles.

The maximum permissible longitudinal tensile stresses to be observed when straightening the rollers on the underside of the rail foot have been limited to a maximum of 250 N / mm ² in EN 13 674-1 "Rail superstructure, symmetrical wide foot rails from 46 kg / m", draft September 1999. Corresponding values can be assumed for the rail head. 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.

Today's high-speed traffic is special high demands on the straightness of rails and their break resistance. Through an optimally straight line Condition of the rails is at low vertical and horizontal vibration excitation a calm Vehicle running guaranteed. Optimal straight Rails are therefore a prerequisite for one high driving comfort and a low dynamic load of the rail vehicles and the track superstructure.

The high on the straight surface of rails the demands made make considerable Bending deformations during roll straightening required. The required can be done differently Do not achieve dimensional accuracy. Such a "sharp" performed roll straightening, however, gets significant Residual stresses.

Also attempts at the development of residual tensile stresses and the processes involved in roll straightening generally using FEM calculations and simulation considerations understand, have not yielded any results that in practice to an immediately usable improvement would have led.

The object of the invention is based on the above-described prior art To create processes for roller straightening, which without additional facilities and means of judging Rails without the risk of high Residual tension enables. In addition, a Straightening machine with simple means be trained to do the necessary technical requirements are sufficient.

• bei dem die Schienen eine Rollenrichtmaschine durchlaufen, welche eine Gruppe den Schienenfuß berührender Richtrollen und eine Gruppe den Schienenkopf berührender Richtrollen aufweist, wobei mindestens die Richtrollen einer dieser Gruppen in Richtung der Schiene anstellbar sind,
• bei dem die Anstellung der anstellbaren Richtrollen so gewählt wird, daß im Einlaufbereich der Richtmaschine, gebildet durch die ersten drei Richtrollen beider Gruppen, an einer Richtrolle ein, verglichen mit den an den nachfolgenden Richtrollen erzielten Verformungen, maximaler Wert der Biegeverformung erreicht wird, und
• bei dem diejenigen Richtrollen, die im Anschluß an die Richtrolle von der Schiene durchlaufen werden, so angestellt werden, daß diese maximale Biegeverformung an den weiteren Richtrollen um jeweils einen vorgebbaren Betrag abgebaut wird.

According to the invention, this object is achieved by a method for straightening rails,

• in which the rails pass through a roller straightening machine which has a group of straightening rollers touching the rail foot and a group of straightening rollers touching the rail head, at least the straightening rollers of one of these groups being adjustable in the direction of the rail,
• in which the position of the adjustable straightening rollers is selected so that in the infeed area of the straightening machine, formed by the first three straightening rollers of both groups, a maximum value of the bending deformation is reached on one straightening roller, compared with the deformations achieved on the subsequent straightening rollers, and
• in which those straightening rolls which are followed by the rail after the straightening roll are set in such a way that this maximum bending deformation on the other straightening rolls is reduced by a predeterminable amount in each case.

Advantageous further developments of the invention Procedures are the associated procedural See subclaims.

In addition, the task is also solved by a Roller straightening machine for straightening rails, including several groups on the one hand on the rail foot and on the other hand straightening rolls on the rail head, by which can be specified by the individual in the group Direction of the rail are adjustable, such that in Infeed area of the straightening machine, formed by the first three straightening roles of the groups, at least one Judging role versus the remaining judging roles of other group with a higher degree of delivery so adjustable is that at the last straightening roll of the infeed area a maximum value of the bending deformation can be achieved.

Advantageous further developments of the invention Roller leveler are the associated subclaims refer to.

Preferably, those roles that in Followed by the straightening role on which the maximum value of the bending deformation is reached from be run through the rail so that the Amplitude of bending deformation on each of these rolls is degraded degressively with the greatest possible degression. This can lead to the development of residual tensile stresses can be avoided particularly effectively. It is cheap in this context furthermore when the roles that the one following the role with the highest Bending deformation positioned rollers are passed through, so that the rails in the Transition area of the elastic-plastic alternate bend be brought into the straight state.

A targeted distribution of the anyway on a low The level of residual stresses across the cross-section the directional rail can be achieved in that starting from an initial setting the employment of rolls of the straightening machine positioned in the outlet area about the ratio of the bending curvatures to the relevant roles is varied from about 0.7 to 1.3.

On a conventional straightening machine according to the invention in the course of the straightening process by employing a Straightening roll maximum bending deformation on a roll caused, which is in contact with the rail foot. This deformation is sufficient to achieve the desired one Achieve straightening effect. The through this maximum Bending deformation caused constant curvature of the Rail is on the subsequently passed straightening roles by alternate bending of the rail with gradual decreasing amplitude reduced.

Surprisingly, it has been shown that this way Rails can be straightened for optimal Show straightness with low internal tensile stresses. Elaborate aftertreatments of the invention directional rail is not required.

Particularly good results of straightening at the same time minimized tensile residual stresses can be achieved if the bending straightening roll at which the maximum Bending deformation is achieved, assigned to the rail foot is. It is also beneficial if the grading of individual deformation steps when reducing the maximum Bending deformation is designed so that the Bending straightening roll on which the last deformation of the rail when gradually reducing the maximum bending deformation is reached, is also assigned to the rail foot. It has been shown that, in particular, such distribution of the gradual "reconditioning" the rail is subject to a minimum of residual tensile stresses can achieve optimized straightness at the same time.

The inventive method can be in excellently on conventionally constructed Perform straightening machines where the straightening rollers of the first group offset in the direction of conveyance of the rail the roles of the second group are arranged. The The spacing of the straightening rolls in a plane is generally called Called division. In practice it is common Rail straightening machines with divisions from 1400 - 1800 mm interpreted. The division of roles on one Straightening machine same, different size or variable be adjustable. The rollers can be in the machine horizontally one above the other or vertically next to one another be arranged.

Conventional straighteners are adjustable Top rollers or equipped with adjustable castors. The alternating ones necessary for the straightening process Bends are in the so-called directional triangles achieved. In known straighteners in question standing type form two straightening roles of the one Group with a standard role of the other group such a triangle. With regard to the invention in this context it is favorable if the Straightening roll at which the highest bending deformation is achieved will be the last role of a Directional triangle is. It is also favorable if the directional triangle in question to which the directional role is assigned at which the highest bending deformation is reached in the lead-in area by the rail through the directional path is arranged. To this Way, the gradual degradation of the highest Bending deformation even on machines with a low Number of rolls done safely. That's how it works method according to the invention, for example Perform straighteners in a known manner seven or more straightening rolls are equipped. It is it with a view to minimizing the Residual tensile stresses cheap, if each odd-numbered straightening rollers assigned to the rail foot are.

Fig. 1

einen Ausschnitt einer liegenden Richtmaschine in einer Draufsicht;

Fig. 2

einen Ausschnitt einer stehenden Richtmaschine in seitlicher Ansicht.

Fig. 3

Vergleichende Gegenüberstellung der plastischen Biegearbeit gemäß Stand der Technik mit dem Erfindungsgegenstand.

The invention is explained in more detail below on the basis of exemplary embodiments in the drawing. They show schematically:

Fig. 1

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

Fig. 2

a section of a standing straightener in a side view.

Fig. 3

Comparative comparison of the plastic bending work according to the prior art with the subject matter of the invention.

The one shown in Fig. 1, in a conventional manner straightened machine R is at least seven Straightening rolls 1 - 7 equipped.

In the straightening machine R rails S are straightened previously generated by hot rolling and not on one shown cooling bed from the final roll temperature Have cooled down to room temperature.

The odd-numbered straightening rolls 1, 3, 5 and 7 of the Straightener R are the rail foot F of the rail S assigned while the even-numbered towards the Rail (S) adjustable straightening rollers 2,4,6 on the Rail head K act. The K assigned straightening roles 2,4,6 are in Direction of conveyance P of the rail S offset in this way the straightening rollers 1,3,5,7 assigned to the rail foot F. arranged that each of the straightening rollers 2,4,6 in With respect to the horizontal in the middle between one Pair of straightening rollers 1,3,5 and 7 is arranged. On in this way the straightening rollers 1, 2 and 3 form the Cornerstones of a first directional triangle RD1. Through the The first three straightening rolls 1 - 3 are the infeed area of the Rail S defined. A second triangle RD2 is shown in reverse arrangement by straightening rollers 2, 3 and 4 formed a third right triangle RD3 through the Straightening rolls 3, 4, 5 etc. The straightening triangles are RD1 to RD3 in Fig. 1 indicated by dashed lines. Between a triangle RD1, RD2, RD3, ... associated straightening rollers 1-7, the rail S in alternately bent.

The straightening roller 2 assigned to the rail head K is so in the direction of the rail foot F, that the rail S in the inlet area (1 - 3) at Passing the straightening roller 3 a maximum bending deformation experiences. Starting with the one that happened afterwards Straightening roll 4 becomes the steady The curvature of the rail S is gradually reduced, in such a way that the employment of the further straightening rolls 4 and 6 turns out to be less than that of straightening roll 2 in the infeed area of the leveler R. The gradation is chosen so that the last one is still plastic significant bending deformation on the rail foot F assigned straightening roll 5 takes place.

The bending curvatures required to carry out the straightening process are given in Table 1 below for two examples. Example 1A relates to rails with normal or small differences in curvature after cooling, while Example 1B applies to rails with larger differences in curvature: straightening roller assignment Embossed curvature k * / v of the rail Example 1A Example 1B 1 rail 0 0 2 railhead 3.6 4.0 3 rail -3.7 -4.3 4 railhead 3.1 3.9 5 rail -1.9 -2.6 6 railhead 0.7 1.1 7 rail 0 0

It can be seen that the maximum bending curvature in both Examples in the area of straightening roll 3 is provided. In this context, a curvature is positive defined when the bend on a straightening roll over the Rail head K takes place, i.e. on reels 2, 4 and 6. The curvatures are defined as negative if the Bending takes place over the rail foot F, i.e. to the Straightening rolls 3 and 5.

In practical tests on rails of the UIC60 profile Quality UIC900A has been shown that on a according to FIG trained straightener in the inventive Procedure after straightening the longitudinal tensile stresses in the Rail head K compared to the usual Procedure setting longitudinal tensile stresses by more than half are reduced.

The straightening machine shown in Fig. 2 is nine Straightening rollers 11 - 19 equipped, of which in the The difference for example according to FIG. 1 is not that Rail head K assigned even-numbered straightening rollers 12, 14, 16, 18, but those assigned to the rail foot F. odd straightening rolls 11,13,15,17,19 in the direction of Rail S are installed and deliverable. The larger number of Straightening rollers 11-19 has the advantage that the means suitable employment of straightening rollers 11, 13 and 15 maximum set curvature of the rail S up to Straightening roll 15 very quickly to a low one Curvature value can be returned, so that at the Straightening rolls 16, 17 and 18 only with a small one Curvature amplitude must be directed.

Table 2 gives an example of the bending curvatures k * / v imprinted on the individual straightening rollers when straightening a rail S in the straightening machine shown in FIG. 2. Starting from such a setting of the straightening machine, it is possible to adjust the residual stress distribution in the straightened rail in accordance with practical requirements by specifically varying the position of the straightening rollers 15, 17 and 19 arranged in the straightening area of the machine. The gradation of the curvatures impressed on the straightening rollers 16 and 17, modified with this objective, is put in brackets in the assigned rows of Table 2. straightening roller assignment Embossed curvature k * / v of the rail 11 rail 0 12 railhead 2.34 13 rail -4.30 14 railhead 3.65 15 rail -1.68 16 railhead 1.0 (1.2) 17 rail -1.2 (-1.1) 18 railhead 0.7 19 rail 0

Just like in Table 1, Table 2 is as positively defines a curvature when the bend is on a roll takes place over the rail head K, i.e. to the Rollers 12, 14, 16 and 18. The curvatures are negative defined when the bend over the rail foot F takes place, i.e. on the rollers 13, 15 and 17. It can be seen that in this example, too, that in the inlet area 11-13 intended straightening roller 13 the highest bending curvature having.

The "related bending curvatures", which are mentioned in Tables 1 and 2, correspond to the bending curvatures k _v in the contact area of the straightening rollers 1-7 and 11-19, respectively, which are related to the maximum possible elastic bending curvature k _{s of} the rail S, whereby k _s = 2 * R _p0.2 / E * h. R _{p0.2 denotes} the 0.2% test limit or the yield strength of the rail steel to be straightened, E the modulus of elasticity and h the height of the profile of the respective rail S. This results in k * / v = k _v / k _s .

In Tables 1 and 2 given above entered gradations are guide values, which indicate the orders of magnitude in which the Connection to the highest bending deformation There are stages of "recovery". Be in practice the maximum bending deformation and the stages of subsequent "reshaping" essentially proportional to the yield strength and Dimensioning behavior of the rail material. The value of the highest bending deformation must be all the greater the greater that after the cooling of the rail S existing curvatures and undulations of the rail S are.

If the values of the maximum bending deformation and the last effective plastic / elastic deformation are determined, the necessary employment of the between straightening roll 3 or 13, at which the highest Bending deformation is generated, and the straightening roller 5 or 16 or 17 on which the last plastic deformation of the Rail S is achieved by looking at the elastic plastic bending of the rail S is determined become. The influencing factors are the technical data the straightening machine R (pitch; diameter, number, type the employment of the judging roles; Deformation of the Straightener R as a result of the straightening process).

Of course, straightening the rails S can also be carried out on straightening machines with more than nine roles are equipped. It turns out that on such machines further lower the Residual stresses can be achieved.

Practical tests on rails of the UIC60 profile in quality UIC900A have shown that on a according to FIG trained straightener in the inventive Procedure after straightening the longitudinal tensile stresses compared to the usual procedure longitudinal tensile stresses on average by 40% are reduced.

FIG. 3 shows a diagram which is shown in comparative comparison the plastic Bending work according to the prior art with the Subject of the invention explained. Figure 3 relates to a roller straightener with seven straightening rollers, like her is shown for example in Figure 1. Above the The number of straightening rolls is the plastic bending work applied. With ⋄ the bending work is in accordance with the Technology and with □ is the bending work according to Subject of the invention meant. It can be seen that the Bending work on the straightening roll in the subject of the invention 3 is highest and compared to the following straightening roles the other curve decreases significantly.

LIST OF REFERENCE NUMBERS

1 - 7

straightening rollers

11-19

straightening rollers

F

Rail foot of the rail S

K

Rail head of the rail S

P

Direction of conveyance of the rail S

R

straightener

RD1, RD2, RD3

Directional triangles

S

rail

Claims (12)

Rail straightening method (S), in which the rails (S) pass through a roller straightening machine (R) which a group of straightening rollers (1,3,5,7; 11,13,15,17,19) touching the rail base (F) and a group the rail head (K ) touching straightening rollers (2,4,6; 12,14,16,18), at least the straightening rollers (2,4,6; 11,13,15,17,19) of one of these groups in the direction of the rail (p ) are employable, in which the position of the adjustable straightening rollers (2,4,6; 11,13,15,17,19) is selected so that in the infeed area of the straightening machine, formed by the first three straightening rollers (1,2,3; 11,12 , 13) of both groups, on a straightening roller (3; 13), compared to the deformations achieved on the subsequent straightening rollers (4,5,6,7; 14 - 19), the maximum value of the bending deformation is reached, and in which those straightening rollers (4,6; 15,17,19) which are followed by the rail (S) after the straightening roller (3; 13) are set in such a way that the maximum bending deformation on the other straightening rollers (4th - 7; 14- 19) is reduced by a predetermined amount. A method according to claim 1, characterized in that those straightening rollers (4,6; 15,17,19), which follow the inlet area (1-3; 11-13), respectively the straightening roller (3; 13), from the Rail (S) are passed through, so that the amplitude of the bending deformation at each of these subsequent straightening rollers (4-7; 14-19) is reduced degressively with the greatest possible degression. A method according to claim 1 or 2, characterized in that those straightening rollers (4,6; 15,17,19) which follow the infeed area (1-3; 11-13), respectively the straightening roller (3,13) , are run through by the rail (S), so that the rail (S) is brought into the straight state in the transition region of the elastic-plastic alternating bend. Method according to one of the preceding claims, characterized in that, starting from an initial setting, the adjustment of the straightening rollers (4 - 7; 14 - 19) forming an outlet area via the ratio of the bending curvatures on the straightening rollers (5, 7 or 15, 17, 19) is varied from about 0.7 to 1.3. Method according to one of the preceding claims, characterized in that the straightening roller (3) on which the maximum bending deformation is achieved is assigned to the rail foot (F). Method according to one of the preceding claims, characterized in that the straightening roller on which the last deformation of the rail (S) is achieved when the maximum bending deformation is gradually reduced 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 one group, viewed in the conveying direction (P) of the rail (S), are offset the straightening roles (2,4,6; 12,14,16,18) of the other group. Roller straightening machine for straightening rails, including several groups from on the one hand on Rail foot (F) and on the other hand on the rail head (K) adjacent straightening rolls (1,2,3,4,5,6,7; 11, 12, 13, 14, 15, 15, 17, 18, 19), of which predeterminable Straightening roles (2,4,6; 11,13,15,17,19) individual of the Groups can be set in the direction of the rail (S), such that in the infeed area of the straightening machine, formed by the first three straightening rolls (1,2,3; 11, 12, 13) of the groups, at least one standard role (2.13) compared to the remaining straightening roles (4.6; 15, 17, 19) of the other group with a larger one Degree of delivery in the direction of the rail (S) see above it is possible that at the last straightening roll (3.13) of the inlet area a maximum value of Bending deformation is achievable. Roller straightening machine according to claim 8, characterized in that the adjustable straightening rollers (4,6; 15,17,19) are adjusted in the direction of the rail (S) in such a way that the amplitude of the bending deformation on these further straightening rollers (4-7; 14 19) can be degraded degressively, in particular with the greatest possible degression, the rail (S) being able to be brought into the straight state in the transition region of the elastic-plastic alternating bend. Roller straightening machine according to claim 8 or 9, characterized in that two straightening rollers (1,3,5,7; 11,13,15,17,19) each of the one group with one straightening roller (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 greatest bending deformation is achieved is the last straightening roller (3; 13) of the inlet area ( 1,2,3; 11,12,13). Roller straightening machine according to one of the preceding claims, characterized in that the straightening machine (R) comprises at least seven straightening rollers (1-7), preferably nine straightening rollers (11-19). Roller straightening machine according to one of the preceding claims, 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).

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