JPS6264422A - Vertical straightening method for local collapse of long rail - Google Patents

Abstract

PURPOSE:To improve the straightening accuracy, and to hold the wear resistance by giving a pre-distortion of a prescribed quantity through an external force to a rail, and subsequently, heating a prescribed range of the rail to a specified temperature, and thereafter, cooling it gradually. CONSTITUTION:First of all, a fastener 7 of a cross tie 8 is released by a portion of 5 or 6 pieces of rails centering around a collapse 3 of the rail 1 which has been laid. A pressure base 9 is installed to the cross tie 8 of both sides of the collapse 3, and also a holding tool 10 is attached to the cross tie 8 next to the pressure base 9. Subsequently, a hydraulic ram 11 is provided under the pressure base 9, and the rail 1 is raised by a hydraulic pump 13. In this case, a pre-distortion of 1.0-2.5mm per 2m length is given to the rail 1. Also, a heating furnace 14 is installed to a rail button part 6, and a range of + or -50mm of the rail height is heated to 750-880 deg.C, and thereafter, cooled gradually. In this way, the rail 1 is straightened exactly by a thermal plastic deformation, and the wear resistance of the top part of the rail can be held.

Description

[Detailed Description of the Invention] [Industrial Use] This invention provides a method for vertically correcting local dents in long rails, which flattens the top surface of the long rail by removing the local dents that have occurred on the top surface of the long rail while it is being laid. No matter what.

[Conventional technology]

High-speed railway rails are made by welding regular length rails of 25 m in length to increase the length from 10 to 1.5 km in order to improve train running stability, reduce second joint noise, and reduce track maintenance costs. rails are used.

Rails are welded using 7-ratunyu welding, gas LL welding, arc welding, or thermite welding, but in any of these methods, the heat generated during rail welding causes the area near the rail weld to be manufactured in a factory. Re/LI has uniform properties as it is: It has different properties from the J key part.

Figure 11 shows the hardness of the top of the rail near the weld when the rail is welded by flat welding, with the horizontal axis representing the distance from the center of the weld (In1N) and the vertical axis representing the hardness of the top surface (HB). An example of Sabu 4j is shown. As is clear from the figure, the part of the brace that is not affected by the heat during welding exhibits a certain level of hardness, but the part that is affected by the heat during welding has a markedly reduced hardness.

As the wheels pass along the top of the rail (j), the part of the top surface that comes into contact with the wheels wears out. Figure 12 shows the amount of wear in the top direction ( ,,
) on the vertical axis; Fig. 11 shows the condition of the back hair 22 on the top surface of the rail with the hardness distribution shown in this figure. The welded portion Mffl is almost flat, but the welded portion Mffl wears into a shape that corresponds to the change in hardness.

For this reason, when a high-speed train runs, significant impact noise is generated depending on the condition of the tread of the rail weld, so in order to maintain or increase train speed, it is necessary to remove minute irregularities on the tread. 0. These minute irregularities can be made flat by only grinding, but if the irregularities exceed a certain limit, the amount of grinding becomes large, which is inefficient and uneconomical.

Conventionally, the vertical rail correction method for removing minute irregularities on the top surface of the rail includes: - An external force that applies a bending load that exceeds the elastic limit of the I/- rail due to atmospheric dryness to cause it to plastically deform; ■ A local heat treatment straightening method in which the head or bottom of the rail is locally heated and cooled using a burner to thermoplastically deform it by tying it with the railroad ties, and the entire cross section of the rail is There is a whole heating straightening method in which the A3 transformation point or higher is heated using a suitable device such as a gas burner, and then an external force is applied to this using a hydraulic device or the like.

[Problem that the invention seeks to solve]

■ The straightening method mainly using external force uses a hydraulic device to perform static bending at around room temperature, and since the amount of bending deformation can be easily adjusted, the finishing accuracy after straightening is good.

However, since the bending device is required to have the rigidity to withstand the large load corresponding to the rail, the bending device is large in size and is usually used for factory or base work.

This is iiJ t! Even if the workability of the i2 type is improved, the following problems may occur when straightening long rails that have been installed for many years. In other words, the top surface of rails that have aged often has surface defects such as scratches, and if large bending stress is applied to correct such areas, the defects may expand due to stress concentration, or if they are significant, may even lead to brittle fracture.

■ The local heat treatment straightening method is simple and does not require special equipment, but the reproducibility of the amount of straightening is poor, and it cannot be straightened if the heating temperature is low, and conversely, if the heating temperature is high, it causes quench cracking, so it is not recommended. There was a problem in that it was difficult to control the degree of correction, and a high level of skill was required to improve the accuracy of correction.

■ In the whole heating straightening method, the entire cross section of the rail is held at l″KlW using a ring burner, etc., so the external force required for straightening is small. However, as a straightening method for long rails that have been laid, the following There is a problem.

Figure 13 shows the results of the rail tensile test, with tensile test 1) on the horizontal axis and tensile strength 1S and #i4 force YS (kg/mm') on the vertical axis. When the entire rail cross section is heated above 750° C., which is the A3 transformation point, the λ·-A strong eaves become smaller and can be easily corrected. However, if the temperature of the rail during straightening is lower than the set temperature, the axial force of the stretched steel will act on the rail, resulting in a state where there is a significant difference in flatness, for example, the temperature of the rail when straightening is lower than the temperature when it was laid. The tensile force (pulling axial force/rail cross-sectional area) at a temperature 40°C lower is approximately 10 kg/mm'. On the other hand, when the entire cross section of the rail is heated, as shown in Figure 11, the double force YS is 7 kg/mm', the tensile strength is more than 9 kg/mm', and the heating range is equal to the tensile force. It becomes impossible to lose weight, and there is a dent in the heating range, that is, a thinning phenomenon occurs. For this reason, correction work during the winter season is severely restricted.

In addition, if i < 3 after heating the entire rail cross section is made gentler, a curved part will occur in the heating range of the top surface of the installed rail that has hardened under rolling load, and this part will wear more selectively than other parts. The condition progresses, and as a result, the corrected area becomes short-lived.

This invention was made in order to solve such problems, and aims to improve Rono Gerono's vertical straightening method, which enables highly accurate vertical straightening without closing the track.

[Means for solving problems]

The vertical correction method for localized dents in long rails according to the present invention is as follows:
The head is on the tension side. L, Apply external force from the shell of the sea urchin rail J and apply a multi-strain of 10 to 25 - per 2 m of rail length. In the range 750℃~880℃
This is a method of correcting local dents in long rails by heating and cooling the rail, and then maintaining the rail head at 300° C. or lower while heating and cooling the rail.

[Effect]

In this invention, after pre-straining the sea) L within the elastic limit, the bottom of the rail is heated above the A3 transformation point to cause thermoplastic deformation, and the rail head is held at 1ζ above 300°C. Prevents softening due to heating of the head part, which in turn prevents a decrease in wear resistance.

〔Example〕

Hereinafter, as shown in FIG.
We will specifically explain how to correct this. In FIG. 1, 4 is the head of the rail 10, 5 is the abdomen, and 6 is the bottom.

First, as shown in Fig. 2(a), the sea nom fastening device: j27 is connected to the sleeper 8, centering on the recess 3 of the laid rail 1.
Release 5 to 6 pieces of the sleepers 8 on both sides of the recess 3.
Install it in position. In addition, holders 10 are attached to the sleepers 8 on both sides of the pressurizing platform 9 to prevent the rail 1 from moving due to lateral pressure (7) and causing gauge expansion even if the train runs during work.

Next, as shown in FIG. 2(b), the i+b pressure rail 11 is installed under the pressure table 9, and is pressurized using the hydraulic pump 13 connected by the port 12 to lift the rail 1. .

Lift up rail 1 until the rail length is approximately 2m J
ix is the recess depth d shown in Figure 3 and the overhang j shown in Figure 4.
It is the sum with lu. The recess depth d is usually 05~20III
As a result of the experiment, Joetsu Mu is about 05 days + i
is appropriate. Therefore, lift up rail 1
The range is 1.0 to 25 m per 2 m of seal length.
becomes. 160kg/m le/L with 2m string 2.5+m
When it is lifted, the tensile stress applied to the rail head 4 is approximately "kg/ni m', and the tensile stress applied to the rail head in the case of the conventional straightening method in which plastic deformation is performed only by external force is approximately It is significantly smaller than 50 kg/+n m'.

Therefore, even if there is some defect such as a crack in the rail on the top surface 2 of the rail 1, there is no risk of the defect expanding or brittle damage.

With the seal [1] lifted as described above, a small 4-sided furnace J4 for heating the bottom is attached to the seal bottom 6 of the 3-hole recess as shown in FIG. 2(C), and a gas burner 15 is used to Heating to a turbidity of 17t: After cooling.

As mentioned above, when the rail bottom 6 is heated with the rail 1 provided with the child claws 1, the bottom 6 of the rail 1 deforms downward into a concave shape due to large thermal expansion. , thermoplastic deformation occurs in the heating range of the bottom part 6, stress relaxation 6 occurs, and after cooling there is a slight convexity as shown in Figure 5! 4r remains,
Seal 1 should be corrected. If necessary after correction, finish by grinding in the L shape shown in Figure 6. 1. When grinding.゛H low difference is -1-0,3~-0,1#Im/
Let it be m.

As a result of experiments, the range of the bottom of the rail heated by the small force j14 was 1.00 to 200 men for 5ON rails, 60
kg/m rail about 1.20-220 mm,
Zunawara 1. --The appropriate height is approximately ±50 strokes.

If the range of the bottom of the rail to be heated is narrow, correction will not be performed sufficiently, and conversely, if this range is too wide, buckling will occur.

In addition, the maximum heating temperature in the rail section ml is 7 at the bottom 6.
50 to 880°C, and 300°C or less at the head 4.

The bottom part 6 is heated to 750°C or higher using rail steel (C;
O1i~0.75%) and (,iΔ3 transformation point is 750
At temperatures below 750°C, the yield point becomes extremely small, resulting in a state where the deformation resistance is lost and thermoplastic deformation easily occurs. Tabata is to perform correction.

The reason why we set the maximum temperature of 880°C for one time (heating of storage section 6) is that if we normalize the rail steel and heat it to a maximum temperature of 880°C or higher, the crystals will form and the material will deteriorate and become brittle. The storage section 6 is equipped with 47 items with a temperature of 880℃ or higher, and the rail head 4
1i! This is because it becomes difficult to maintain the temperature above 300°C.

Rail head 4 TS230 Heating to Q℃ is as follows:
As shown in Figure 13, below 300°C, the tensile strength r s
, rq4 force YS does not decrease, no Europeanized part occurs on the seal top surface 2 hardened by rolling load, and M6↓・L
This is because the sex is not impaired.

In FIG. 7, the time from the start of heating (1m1n) is plotted on the horizontal axis, and lmf1. f (Heating rail 1, taking ℃l as the vertical axis)
An example of the heating/cooling curve of each part of the 1.-ru when cooled is shown. The heating/cooling curve shown in the figure shows the rail temperature between 6 and 1.
In the case of 2℃, a is the parietal surface, bl is the center of the acquisition area, and C
is the heating/cooling curve centered at the bottom.

This heating/cooling curve is first applied to the rail bottom 6 at the Konashi furnace 14.
Heating (7, rail bottom 6 is 1 f constant t exaltation example left 7)
When the temperature reached 50°C, the gas burner 15 was extinguished, and then the temperature at the bottom of the rail 6 reached 30°C.
Once it reaches about 0°C, cool it with water.

During this heating and cooling, the maximum heating temperature of the seal H1 part 5 is 5
00℃ or less, maximum heating of top surface 2; quality is 300℃9
．． It's below.

As mentioned above, the temperature of the rail bottom 6 is 750°C.

Once in the abdomen 5 is below 500℃ 2 Once in the top of the head 1 fj 2 is 3
When the temperature is below 00℃, the proof strength of rail 1 is approximately 25kg/m
m', the tensile strength is approximately 45 kg / nn m', and even in winter when the temperature is -40°C from the set temperature, the rail strength is approximately 10 kg / +nm'. It is safe beyond all limits.

Next, we will show the results of straightening the rail 1 in detail according to the above embodiment.

Corrected the dent on the head Ia surface 2 that occurred in the stationary section of the 60kg/m Ronograil that had been installed and used for many years on high-speed railways. In this correction, the number of tightening devices for the sleepers was 6, the rail temperature was approximately 6 to 12°C, and the heating and cooling range of the seal was set to about 200 degrees at the rail J hole 6, as shown in Figure 7. The heating and cooling curves shown were applied.

When correcting M of L-/l, the length of the rail shown in Figure 8 L = 2 cn
+72m) and correction group y (1oI11/2m)
Figure 9 shows the relationship between

A linear tendency between the lifting force X and the correction My (regression equation y
= 1.095 -0,537 hail, correlation coefficient r
! , tO, 908, and the lifting force X and the correction base y show an almost perfect correlation, and the correction accuracy is extremely high.

In addition, Fig. 10 shows the hardness of each part after straightening, with the horizontal axis representing the distance from the center of the weld (1 (sl)) and the vertical axis.
As shown in Figure 0, the hardness of the head If im 2 does not change due to heating, and it can maintain the hardness of J+ before orthodontic treatment after orthodontic treatment.

〔Effect of the invention〕

As explained above, this invention provides SEENO F with predictions within the elastic limit! After heating, heat the bottom of the rail to a temperature above the A3 transformation point to thermoplastically deform it, and heat the top of the rail to a temperature of 300°C.
Because the rail is vertically straightened by keeping it below ℃, C.1 has sufficient tensile strength even when m is positive.

ctI)j! with high precision without reducing the T-rail cross-sectional area and without track closure, which often occurs with conventional straightening methods! Since the hardness of the rail parietal surface does not change even after correction, the durability and strength of the rail parietal surface can be maintained.

Furthermore, since it does not apply large tensile stress to the rail head,
It also has the effect of preventing the expansion of minute flaws that existed on the top of the head.

[Brief explanation of drawings]

Figure 1 is an ↑) perspective view of Seeno L, Figure 2 (al, (b)) is an explanatory diagram of the 'A embodiment of this invention (cr, (d) + side), and Figure 2 (a) is Plan view, Figure 2 (bl is Figure 2 (al)
The Δ-A sectional view of FIG. 2(c) is the F3-A cross-sectional view of FIG. 2(c).
3 sectional view, 214(d) is a C-C sectional view of FIG. Figure 8 is an explanatory diagram of ``Hold it up!''
+'E,my's holding diagram, Figure 10 is the parietal direction hardness 4\min 4i diagram, Figure 11 (Yoronge 1-1-・L melting time rail head ro, 1iII hardness part III l!”4, 1st
Figure 2 is a map of the welding area, No. 1: (1j-41i
, I L - Temperature of L - π2 Strength, Il] J Strength 4. 1. Rail, 2; Top of head, 3: Concave Y book, 4: Head, 1
') Daibe. Agent PuC Rijo Sato Toshi Collection Figure 1 Figure 2 t^1 Intestine (b) (c) (d) Figure 3 Fan 4 Figure 6 Figure 7 Sword t7 Ri to r4 Jifuneichi et al. RiyatohaJ'i (mint
8th sentence, Figure 9, weight x (mm/2m) Figure 10, diagonal elevation t7b*”=f) i!k (mm) Figure 11, 12 vl outside r, h (mrr+) Figure 13

Claims (3)

[Claims] (1) Centering around the local concave position on the top surface of the long rail, apply an external force from the bottom of the rail so that the head is on the tension side to give a pre-strain of 1.0 to 2.5 mm per 2 m of rail length, In this state, the length direction of the bottom of the rail, which is under compressive stress, is covered with a heating furnace within ±50 mm of the rail height.
A vertical correction method for localized dents in long rails, which involves heating to 0°C to 880°C and then gradually cooling to cause thermoplastic deformation. (2) The method for vertically correcting local dents in a long rail according to claim 1, wherein the rail head is maintained at 300° C. or lower during heating and cooling of the rail. (3) If necessary, the top of the rail head is further ground to correct local dents in the rail. Claims 1 and 2
Vertical correction method for localized dents in long rails as described in Section 1.