1. HP bond peel off
Rail bond proceeds to destroy gradually with severe rail vibration.
In case of the HP type rail bond, it appears the peel off the brazing part.
In case of bond for DC, it appears the peel off at the side of conducting current wire and proceeding this peel off to the end part side. (Fig. 1)
In case of bond for AC, it appears the peel off initially at the four corners of brazing part and proceeding the peel off elliptically. (Fig. 2)
It reaches to destroy after approx..80 percent peel off either bond for DC or AC.
It will be possible to eliminate the destroy with inspection to find the starting peel off because it takes much time until destroy with expanding peel off.
Foot note 1: In the condition of 1.2 to 1.8 million G of vibrating acceleration,
it will be equivalent to approx.600 thousands hit (on our experience) until proceeding to 20 percent peel off rate which is same as annual run total 20 million tons on the rail and period of approx. 4 months.
Fig.1 HP bond peel off pattern (for DC)
Fig.2 HP bond peel off pattern (for AC)
2. Confirming peel off
It is possible to confirm the proceeding peel off on the manner shown in Fig. 3.
However, every condition on the above Figures seems to be not comply with any bond. (we are now doing investigation)
Fig. 3 Inspection manner for peel off
3. Development of hammering sound test device
On the carrying out maintenance, confirming the peel off is very important.
In this matter, it will be necessary to inspect quantitatively without sensual manner.
On this purpose, we are still studying this inspection manner collaborated with Fukuoka Industrial Technology Center Mechanics and Electronics Research Institute and SHINNIPPON NONDESTRUCTIVE INSPECTION Co. ,Ltd.
In the view of difference of hit sound and analysis of hit sound wave, we caught the characteristics of hit sound against the bond with proceeding peel off.
It was confirmed to detect the peel off part on the probability of 95 percent.
We already made prototype device and still try to produce it on commercial basis. (Figure 4 and Figure 5)
Fig. 4 Analysis result with hit sound wave ( wave nature)
Fig. 5 Prototype Device
4. Working for maintenance
Even it is super durable bond, it will be difficult to make protective maintenance without foreseeing peel off problem and also difficult to keep stable operation of the system.
We wish to continue the investigation for safer operation of track circuit and economical possibility through our total offer including production, construction and maintenance technology.
