1. What is the rail brazing?
This is one of methods adopted since the time of Japan National Railway. It took for countermeasure of train detecting error at the track circuit.
In case of contact type detecting system, one of reasons for train detecting error is to be caused by rust of rail. This rusty problem reduce the efficiency of conducting current.
It will be difficult to have perfect shut off the current at track circuit due to increasing electrical resistance between train wheel contact point to rail and track circuit rail.
On this situation, it took another way for protecting rust at rail by means of another high conducting current metal is to be brazed on the rail top.
In the old time, it was brazed thin metal called rail plating method ( Actually this is brazing method which is not meaning of plating )
2. History of changing the rail brazing method
In the old time, it was brazed metal material to rail top directly.
This method sometimes happens wrong conditions such as peeling off the metal by friction, as well as the abnormal noise or impact to the train caused by some foreign material stacking between train wheel contact point and rail top surface.
In order to solve such wrong conditions, it was devised to braze the metal into groove after making it to rail top surface.
Since this method developed in the time of Japan National Railway, brass solder as the brazing material is to be still adopted up to date.
However, this brass brazing method should have various limitations. Therefore, it is limited for workable rails and scope of application.
In this situation, it was successful for us to newly develop the silver alloy brazing method in order to remove the limitation with brass brazing method.
３．History of development for silver alloy brazing method
It seems that the technology of rail brazing belongs to metallurgy and welding category. It is quite different for us to take part in this brazing technology which is apart from our main business of signal construction works.
However, we used to have experience about the rail welding works and the rail plating works for a while in our company’s history.
Afterward, we did withdraw rail welding works.
However, this is founded of our development with silver alloy brazing method based on the technology and skilled matters built up through the above experiences.
In order to innovate the conventional brass brazing method, we did try to develop new working material since year of 2005.
Finally, it was successful to solve the heat affection problem given to the rail with applying silver alloy solder.
Furthermore, after our continuous improvement on this working, JR East Japan Company adopted officially this method and additionally approved it in 2007 for listing at “Signal Facilities Design & Works Standard”.
We are still doing our best to eliminate the bad affection of heating to the rail.
It was not successful for us to develop such new brazing method without metallurgy and welding technology. In this our development works, we have received direction by Nittetsu- Sumikin Technology Corporation ( Former Kyushu Techno Research Co., Ltd.) .
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