Method and system for welding railroad rails-4

Method and system for welding railroad rails-4

Ceramic Welding Backing | Ceramic Backing Welding| Ceramic Backing Taps

In accordance with another aspect of the invention, the thin metal insert or consumable backing plate used to support the root pass as it is laid in place is held below the ends of the rail by protruding tabs and is supported on a ceramic tile. The backing plate spans the gap between the two objects being welded which, in the preferred embodiment, are the ends of railroad rails. By using a thin consumable backing plate, there is a possibility of arc blow through whereby the arc penetrates completely through the backing plate. Such arc blow through or blow through hole is not desirable as the wire moves transversely across the backing plate. The structural defect of a blow through is corrected by using the present invention. The disadvantage of this blow through is that it tends to create a cutting action as the torch swings transversely across the insert. To prevent such blow through, it is necessary to keep a puddle of metal under the arc as it is advancing between the rails. When the torch is moved too rapidly and is ahead of the weld puddle or the weld puddle flows away from the arc, the propensity for an unwanted arc blow through is substantially increased. Thus, it is advantageous to prevent the cutting action of a blow through by maintaining a wire movement speed along the selected path at a rate where a molten puddle is maintained between the arc and the plate being consumed. This can not always be done; therefore, the present invention provides an arrangement for detecting and compensating for unwanted arc blow through as the electrode or wire pivots between the ends of the rails. Blow through is detected by a monitoring system based upon a reading or sensing of the weld current. When the welding arc punches through the insert, the wire stick-out ESO from the torch increases. This causes an increase in the resistance of the welding operation. The power supply used in the welding method and system has a constant voltage control. The voltage is maintained constant by the power source. As the resistance increases during an arc blow through, the welding current has a corresponding decrease. Consequently, there is a direct correlation between the electrode stick-out and the welding current. By measuring or sensing the current, a blow through can be detected by a current decrease below a certain value. This value changes with various welding wires used in the root pass welding process. A primary aspect of the present invention provides a corrective response to an arc blow through occurring when the torch is swinging between the rails. The corrective action prevents a cutting process in the very thin backing plate. In the primary or practical implementation, the wire is moved back to the starting point of a transverse swing when a blow through is sensed. A second embodiment includes merely moving the wire back a short distance when a blow through is sensed in a transverse swing of the wire.

Date: 2023-04-10     hits: 390    Return