| 摘要 |
<p>Valve gated injection molding apparatus with a spring (120) mounted on a central pin (124) adjacent the head (86) of a valve member (80) in a spring chamber (104) in each of the pistons (90). The spring (120) is compressed between the base (126) of the pin (124) and the cap (114) of the piston (90) to preload it. When the valve member (80) and piston (90) are driven forwardly to the closed position, the head (86) of the valve member (80) retracts somewhat into the spring chamber (104) against the force applied forwardly against the head (86) of the valve member (80) by the spring (120). This cushions the impact of the front end (84) of the valve member (80) in the gate (16) and provides for tight seating of the front end (84) of the valve member (80) in the gate (16) without requiring all of the components to be made to precise tolerances with exact allowance for thermal expansion. The spring (120) is a number of selected disc springs stacked in sets facing in opposite directions, from which the force applied to the head (86) of the valve member (80) is predetermined.</p> |
