Patent ID: 8658935

Claim:
A method for creating, under control of a programmed controller, an in-track weld between a first rail segment and a second rail segment via a welding head having two clamp assemblies connected by a closing actuator, the two clamp assemblies being drawn together at a desired rate by the closing actuator, during an in-track weld operation, to cause the first rail segment and the second rail segment to approach one another and thereby enable an electrical current to pass between the first rail segment and the second rail segment, the method comprising: applying a voltage difference between the first rail segment and the second rail segment; actuating the closing actuator to exert a closing force causing the first rail segment and the second rail segment to approach such that the electrical current passes between the first rail segment and the second rail segment; controlling a rate at which the two clamp assemblies are drawn together by the closing actuator so as to control relative movement of the first rail segment to the second rail segment to maintain the electrical current close to a predetermined electrical current value; measuring, during the applying and actuating, a pressure relating to the closing force exerted by the closing actuator; determining, as a result of the measuring, a rate of change value for the pressure relating to the closing force exerted by the closing actuator; detecting, based upon the rate of change value, whether the closing force has changed faster than a threshold rate of change; and actuating in response to the detecting, a control element for the closing actuator to facilitate drawing the clamp assemblies together at the desired rate.