| 摘要 |
Apparatus for welding plastic profiles together has slides to which the ends of the profiles to be welded are clamped, the slides then moving inwards to bring the ends to the hot plate, where the softened ends are then held under a multi-stage force as the cool and has a drive mechanism for the slides which contains a closed hydraulic circuit to produce the multi-stage force. Pref. the closed hydraulic system comprises two concentric pistons, one inside the other, their different areas producing two stages of applies force; the pistons are moved by an external mechanism, and the cylinder containing them is moved and actuates the slide mechanism. The cylinder chamber is connected to a further hydraulic reservoir containing a spring-loaded piston. The system enables a multi-stage force to be produced without any valves or pumps in the hydraulic circuit. |
