| 摘要 |
This invention relates to an injection molding system having a valve pin which is hydraulically actuated between an open and a closed position in which its tip end is seated in a gate leading to the cavity. The actuating mechanism includes a piston secured to the driven end of the valve pin which reciprocates in a cylinder. The cylinder has an inner cylindrical member which is brazed in an outer member with a flanged portion. Separate hydraulic fluid ducts extend from the flanged portion through the outer member, along grooves in the outer wall of the inner member and then through holes through the inner member to conduct hydraulic fluid to opposite sides of the piston. The flanged portion of the outer member has a pair of passages extending through it, each connected to one of the ducts. Alternate ends of the passages are sealed off so that hydraulic fluid may be received either from supply lines drilled through the back plate in which the cylinder is seated or an abutting top plate. This structure provides the advantage that the hydraulic fluid supply lines need not be drilled through the back plate if the system layout is such that there is a danger this could ruin the back plate. |
