JPH08224673A - Method for joining rails - Google Patents

Abstract

PURPOSE: To effect joining of rails without melting by inserting an inserting material having lower m.p. than the rail into a gap between the joining surfaces of the rails and holding at the prescribed temp. for a fixed time while pressurizing. CONSTITUTION: The heating degree of a high frequency induction heating coil 6 and the pressurizing force of a movable chuck 4 are controlled and also, these are controlled so as to become the setting values based on the feedbacks of the temp. at the joining part detected with a radiation thermometer 7 and the pressure at the joining part detected with a pressure gage 9. As the inserting material 5, a sheet or powder of Fe-Si-B alloy, etc., having the lower m.p. than the m.p. of the rails 1, 2 is used and inserted into the gap between the joining surfaces of the rails 1, 2 and a movable chuck 4 for holding the rail 1 is advanced to pressurize the joining part. The joining part is heated and held at the intermediate temp. between the m.p. of the rails 1, 2 and the m.p. of the inserting material 5 with the high frequency induction heating coil 6. By this method, only the inserting material 5 is melted, invaded and diffused into the base material of the rails 1, 2 and can firmly be joined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rail joining method used as a rail.

[0002]

2. Description of the Related Art From the viewpoint of improving the riding comfort of trains such as vibration and noise and improving the service life of rail joints accompanying the speeding up of trains, rails have been lengthened in order to reduce the number of rail joints. There is a limit to the length of the rail that can be carried into the laying site, and rail joining work at the site is unavoidable. As the rail joining method on site, thermite welding method, gas pressure welding method, flash butt welding method, and closed arc welding method have been conventionally used, but in terms of stability of joint quality and joint efficiency, Not enough results have been obtained.

[0003]

SUMMARY OF THE INVENTION Therefore, the present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a rail joining method capable of obtaining a joined joint with stable joint quality in a short time. Is.

[0004]

To this end, a rail joining method according to the present invention is applied to rail joining of railroads, etc.
Between the bonding surfaces of the pair of rails to be joined, inserting the insert material having a lower than their rail melting point (T _R) melting point (T _i), the joint while applying pressure to the joining surface T _i
<T (T _R) A rail joining method, characterized in that both rails are joined without melting by heating to a temperature of T _R and holding at that temperature for a certain period of time. In the method, the melting point (T _i ) of the insert material is 1200 ° C. or lower.

Further, the present invention is characterized in that, in the above-mentioned rail joining method, an insert material having a thickness of 80 μm or less is used.

Further, the present invention is characterized in that, in the rail joining method, the joining portion is heated at a frequency of 400 KHz or less by using a high-wave induction heating method or a direct current heating method.

Further, according to the present invention, in the method for joining rails, the joining temperature is ≦ 1300 ° C. and the pressure applied to the joining surface is ≧ 1 M.
It is characterized in that the joining is performed under the conditions of Pa, holding time at the joining temperature ≧ 60 sec, and roughness of the joining surface Rmax ≦ 100 μm.

Further, the present invention is characterized in that, in the rail joining method, the joining portion is joined in an inert gas atmosphere.

In the rail joining method according to the present invention, the joining surface is 1 mm farther than the rail surface to be joined.
After being inflated and joined as described above, it is characterized by being finished smooth by a method such as grinding with a grindstone.

[0010]

[Operation] The joining material is joined by heating the joining part to a temperature of T _i <T <T _R and melting the insert material and holding it at that temperature isothermally. Therefore, the rail base material is not melted, and extremely Can be joined in a narrow range. Therefore, since there is almost no region of low hardness as in the case of using the melt-bonding method such as thermite welding method or enclosed arc welding method, local wear of the joint can be prevented and the pressure is constantly maintained. Since it is joined by welding, welding cracks unlike in the case of the fusion joining method do not occur. Further, as compared with the case where the joining is performed using the flash butt welding method or the gas pressure welding method, the bulge (burr) of the joined portion can be suppressed, so that the removing work can be performed very easily and in a short time.

[0011]

Embodiments of the present invention will now be described with reference to the drawings. Fig. 1 shows a schematic view of this rail joining device.
And 2 are rails to be joined, 3 is a fixed chuck that holds the rails, 4 is a movable chuck that holds the rails, 5 is an insert material inserted between the joining surfaces of both rails, and 6 is A high frequency induction heating coil for heating the joint portion, 7 a radiation thermometer for detecting the temperature of the joint portion in a non-contact manner, and 8 a gas shield for the joint portion by spraying an inert gas such as nitrogen gas or argon gas. A gas spray nozzle, 9 is a strain gauge or a pressure gauge provided on a fixed chuck for detecting the pressure applied to the joint surface,
Reference numeral 10 is a control device for controlling the heating by the high frequency induction heating coil 6 and the pressing force by the movable chuck. The control device 10 includes the temperature of the joint detected by the radiation thermometer 7 and a strain gauge or a pressure gauge 9.
The pressures of the joints detected at are fed back so that they can be accurately controlled according to the set values.

Although not shown in the drawing, the control device 10 is sprayed with an inert gas at a timing, time, pressure,
It includes a mechanism to control the flow rate and a mechanism to set and control the time to keep the temperature at the junction temperature. The insert material 5 is Ni-Si-B (melting point 1050 ° C) or F having a melting point lower than that of the rails 1 and 2 (about 1470 ° C).
e-Si-B (melting point 1170 ° C) alloy, etc. thickness 80 μm
Use the following sheets or powders.

Then, the insert material 5 is inserted between the joint surfaces of both rails to move the movable chuck 4 forward so that the joint portion is kept at a constant pressure of 3 MPa, and the joint portion is subjected to high frequency up to the joint temperature by the induction heating coil 6. Induction heat and hold at that temperature for at least 60 seconds. As a result, only the insert material 5 is melted and penetrates into the base materials of the rails from the joint surfaces of the rails 1 and 2 to diffusely bond the joint surfaces.

Table 1 shows the results of a bending test and a fatigue test of a 60 kg rail (JIS E1101) joined joint joined under the above conditions by using the insert material 5 having different materials and different melting points.

[Table 1]

In Table 1, Example 1 is a case of joining by a conventional gas pressure welding method, Example 2 is a case where an insert material is not used, and Examples 3 to 5 are examples of the present invention. As described above, according to the joining method of the present invention, an excellent rail-jointed joint having high bending strength and fatigue strength was efficiently obtained.

Further, Examples 6 to 8 in Table 2 show the joining results when the thicknesses of the insert materials were made different. Example 3 in Table 1
When compared with Example 4 and the thickness of the insert material exceeds 80 μm, the rail-bonded joint strength does not sharply decrease, but the rail-bonded joint breaks or breaks at the bonding interface. Must be less than 80 μm.

Further, Examples 9 and 10 in Table 2 are the bonding results when the frequencies of the high frequency induction heating are made different, and are compared with Examples 3 and 4 in Table 1 and Examples 6 and 7 in Table 2 together. When the frequency exceeds 400 KHz, the strength of the rail joint joint does not drop sharply, but the rail joint joint breaks or breaks at the joint interface, so the frequency is 400 KH.
Must be z or less.

[Table 2]

In Example 11 in Table 3, the joining temperature is 1350 ° C.
Table 3 shows the joining results in the case of
When compared with Examples 6, 7, and 9 of No. 1, the bonding temperature is 1
If the temperature exceeds 300 ° C, the strength of the rail-bonded joint will not drop sharply, but the rail-bonded joint will break or break at the bonding interface, so the bonding temperature must be 1300 ° C or less.

Further, Example 12 in Table 3 shows the bonding results when the holding time at the bonding temperature was 30 seconds, and is compared with Examples 3 and 4 in Table 1 and Examples 6, 7, and 9 in Table 2. Then,
If the holding time at the joining temperature is less than 60 seconds, the strength of the rail-jointed joint will not drop sharply, but the rail-jointed joint will break or break at the joining interface, so the holding time at the joining temperature must be 60 seconds or more. .

In addition, Example 13 in Table 3 shows the joint surface roughness (Rma
x) was set to 150 μm, and when compared with Examples 3 and 4 in Table 1 and Examples 6, 7 and 9 in Table 2, when the joint surface roughness (Rmax) exceeded 100 μm. Since the rail joint joint strength decreases and the rail joint joint breaks and breaks at the joint interface, the joint surface roughness (Rma
x) must be 100 μm or less.

In Example 14 of Table 3, the applied pressure is 0.5 MPa.
Table 3 shows the joining results in the case of
Comparing with Example 6, Example 7, and Example 9, the applied pressure is 1M.
If it is less than Pa, the strength of the rail-joint joint is reduced, and the rail-joint joint is broken or damaged at the joint interface.
Must be above MPa.

In addition, in Example 15 of Table 3, the bulge of the joint is 0.
When the joint results are set to 5 mm and compared with Examples 3 and 4 in Table 1 and Examples 6, 7 and 9 in Table 2, when the bulge of the joint is less than 1 mm, the rail joint joint strength is rapidly increased. However, since the rail-jointed joint is damaged at the joint interface in the fatigue test, the bulge of the joint must be 1 mm or more.

[Table 3]

Further, Examples 16 and 17 in Table 4 show the effect of using the shielding gas, and when compared with Examples 3 and 4 in Table 1 and Examples 6, 7 and 9 in Table 2, the shielding gas is If it is not used, the bending strength of the rail-jointed joint does not drop sharply, but the fatigue strength drops and damage occurs at the joint interface, so a shield gas is necessary.

[Table 4]

As described above, according to the present invention, rails can be joined to each other in a short time, and moreover, both rail joining surfaces can be joined without being melted. There is an advantage that the material does not deteriorate.

[Brief description of drawings]

FIG. 1 is a schematic view illustrating an embodiment of a rail joining method according to the present invention.

[Explanation of symbols]

 1 rail 2 rail 3 fixed chuck 4 movable chuck 5 insert material 6 high frequency induction heating coil 7 radiation thermometer 8 gas spray nozzle 9 strain gauge or pressure gauge 10 controller

Claims (7)

[Claims] 1. When joining rails of a railroad or the like, an insert material having a melting point (T _i ) lower than the melting points (T _R ) of the rails is inserted between the joining surfaces of a pair of rails to be joined, and the joining is performed. While applying pressure to the surface, bond the joint with T _i <T <
Method of joining rail, characterized by bonding without melting the rails by heated to T _R becomes the temperature held for a given time at that temperature. 2. The melting point (T _i ) of the insert material is 1200.
The method of joining rails according to claim 1, wherein the temperature is not higher than ° C. 3. The rail joining method according to claim 1, wherein the thickness of the insert material is 80 μm or less. 4. The rail joining method according to claim 1, wherein the joining portion is heated at a frequency of 400 KHz or less by using a high frequency induction heating method or a direct current heating method. 5. A bonding temperature ≦ 1300 ° C., a pressure applied to the bonding surface ≧ 1 MPa, a holding time at the bonding temperature ≧ 60 se
The rail joining method according to claim 1, wherein the joining is performed under the condition that c and the roughness of the joining surface are Rmax ≦ 100 μm. 6. The rail joining method according to claim 1, wherein the joining portion is joined in an inert gas atmosphere. 7. The method according to claim 1, wherein the surface of the joint is expanded by 1 mm or more from the surface of the rail to be joined, and then the surface is smoothed by a method such as grinding with a grindstone.
The method for joining rails according to 3, 4, 5, and 6.