Flash-Butt Rail Welding Machine

Overview

A flash-butt rail welder joins two abutting rail ends by electrical resistance heating and mechanical squeezing. Two rails are clamped vertically end-to-end with a small gap. The transformer secondary (extremely high current, very low voltage) is connected to the clamps, and electrical resistance generates intense localised heating. The rail ends reach plastic deformation temperature, at which point the Upset Pressure System applies massive axial force, squeezing the molten zone and fusing the rails.

How it works

The two rails are positioned vertically and clamped in the Fixed Clamp Block and Moving Clamp Carriage. Misalignment is corrected by the Rail Alignment System system using fine hydraulic cylinders. A capacitive Gap Sensor monitors the gap between the rail ends.

When the welder initiates a cycle, the Moving Clamp Carriage moves forward, closing the gap to 2–3 mm. An SCR thyristor controller ramps up secondary current, and the air gap arcs at the rail contact surfaces. Timing is critical: when the ends reach the right temperature, the Upset Pressure System applies a high-pressure pulse, squeezing the molten zone and bonding the rails. The Milling and Shear Head then cuts away the flash bead.