Flash butt welding machine, esp. for railway rails - where hydraulic circuit contg. adjustable control valves is used to adjust welding gap between rails

摘要

The machine includes two pairs of clamps, each pair being used to hold one workpiece, e.g. a rail by jaws fed with electric welding current. During the initial flash, one pair of jaws can be moved towards the other by a pair of hydraulic jacks. The jacks are fed with hydraulic fluid at a controlled pressure by at least one distributor and a flowmeter ensuring a linear variation in the flow of the hydraulic fluid to the jacks. The linear variation in fluid flow is achieved by using an auxiliary hydraulic cylinder provided with adjustable non- return valves on both sides of its piston. The two rails being welded together can be moved towards each other at a sufficiently low speed, e.g. 0.5mm/second, at the start of welding, and can then be moved at an increased speed, e.g. 1mm/second, to produce a constant distance during the flash.