| 摘要 |
<p>The combined pneumatic-hydraulic press head (1) includes a body (2) inside which a substantially cylindrical main chamber (3) is defined; the chamber (3) accommodates a main piston (4) and a secondary piston (5) so that they can slide along an axial direction (3a). The main piston (4) has a stem (4a) which protrudes from an axial end (6) of the main chamber (3), and the secondary piston (5) is spaced from the main piston (4) on the side opposite to the stem (4a). The two pistons (4,5) sealingly divide the main chamber (3) into three chambers: two end chambers (14,15), which can be connected to a source of compressed air or to the atmosphere in order to move the two pistons (4,5) along the axis (3a) of the main chamber (3) during the approach of the main stem (4a) or spacing motion with respect to the part to be treated (8), and an intermediate chamber (16) which contains a liquid. An actuation stem (19) is furthermore accommodated in the main chamber (3) and sealingly passes through the secondary piston (5). A partition (20) is arranged in the intermediate chamber (16), is rigidly fixed to the walls of the main chamber and is crossed by a passage (21) for the actuation stem (19). The press is actuated by pushing the actuation stem (19) through the passage (21) toward the main piston (4) so as to increase the pressure in the region of the intermediate chamber (16) which is located between the main piston (4) and the partition (20). <IMAGE></p> |
