| 摘要 |
<p>A shield for a flash butt welding apparatus has semi-circular metal plates (40) each secured to a respective electrode portion (16,18,24,26) of two clamping electrodes. A flexible glass fibre wall (46) is secured to the outer periphery of each plate (40) and the outer peripheries of opposing flexible walls (46) are stitched together, thereby forming an envelope having upper and lower portions surrounding a welding area between the electrodes. The upper and lower envelope portions move with the electrode portions to which they are secured. The positioning of two workpieces (20,22) to be joined is permitted by raising the upper electrodes (24,26) and the upper envelope portion, and when the upper electrode portions (24,26) are in their clamping positions, the upper and lower envelope portions form a volume around the welding area. Inert gas is fed to the interior of the envelope via an inlet (52) in order to exclude air from the weld area, and the relative movement of the two electrodes which is essential in flash butt welding is permitted by means of the flexible wall portions (46). <IMAGE></p> |
