What is the segmented welding of seamless rails?
The laying of super-long seamless lines is carried out by welding the unit rails in sections. The key is to ensure that the locking rail temperature does not exceed the limit (in the design and rail temperature range) during welding. Therefore, there are generally two construction methods according to the construction rail temperature and construction conditions, one is called "joining method" and the other is called "insertion method".
1. Joining method
When the joining method is used for construction, the beginning of the unit rail to be laid is welded with the end of the unit rail laid the day before by welding within a skylight time. When laying, welding and releasing are carried out at the same time, so as to achieve one-step completion. In other words, under the condition that the locking rail temperature is considered to be consistent, after the new rail is introduced into the gantry of the rail-changing vehicle, the rail-changing vehicle welds the beginning of the long rail while moving forward. This type of construction organization is more difficult and is generally suitable for the laying of closed lines and the conditions where the rail temperature does not change much and is the same as the locking rail temperature.
2. Insertion method
In a skylight, as in the laying of ordinary seamless lines, a buffer rail (not less than 6m in length) is set between the two unit rails. In another skylight, the buffer rail is taken out, and the calculated rail length is inserted to release the stress, and then the final welding is carried out. The second welding operation can be carried out in the same skylight when the new rail section or the adjacent section is laying the new unit rail. The interval between the work sites should not affect each other's construction, and it is best not less than three unit rail lengths.
In principle, this construction method can be laid at any rail temperature, the construction difficulty is relatively small, and it is easy to achieve uniform temperature and force, which meets the design and rail temperature requirements.
The basic principle of the super-long seamless line is the same as that of the ordinary seamless line. Therefore, all maintenance and repair methods of ordinary seamless lines are applicable to super-long seamless lines. However, due to its special rail length, the super-long seamless line also has some characteristics different from ordinary seamless lines.
Once the super-long seamless line is locked, its locking condition is not easy to change due to its super-long length. For example, when the locking rail temperature is inaccurate and the axial force is unevenly distributed, only local adjustments can be made, and it is almost impossible to release the whole. Therefore, "locking the rail temperature accurately" is particularly important for super-long seamless lines.
