| 摘要 |
A bead projecting from a butt- welded joint between two thermoplastic parts is flattened by re-heating the joint to at least the fusion temperature of the thermoplastic material thereof, pressing the bead flat against the joint, and rapidly reducing the temperature of the pressed thermoplastic material by circulating air. The re-heating and pressing may be effected on each side of the joint by a device comprising an electrically heated titanium alloy strip 21, Figure 2, backed by a ceramic or high temperature polyamide insulating strip 19. Cool air is blown through a trough 25 in the strip 19 and through holes 23 in the strip 21 after heating. A modified device, Figure 3, comprises a heated strip 31 and an insulating strip 29 with grooves 33, 35 through which ambient air is sucked in by a pump. The thermoplastic parts may be polyethylene or ethylene-propylene copolymer parts of a battery jar. <IMAGE> |
