Nozzle for injection of elastomers into a molding tool has an insert with material flow channel and external axial drive system to eliminate a runner

摘要

The nozzle is mounted on a cold runner block between a plasticizing unit and molding tool(150). A needle(74) which closes the nozzle outlet(75), forms the nozzle outlet end of an insert(70). The insert is moved axially in the main flow channel by an external drive unit and incorporates has a material flow channel(72). The insert drive unit comprises a short stroke cylinder(160) connected via rods(40) to a holding ring(50) outside the nozzle body(3). The holding ring surrounds the nozzle body close to the insert(70) and can be moved axially. Bolts(77) arranged radial to the nozzle axis have inward facing ends extending into a ring-shaped recess(76) in the insert. The flow channel in the insert ends in bores(73) which enter an outer nozzle ring(2) prior to the start of the needle area(74). The outer nozzle ring comprises a conical threaded ring which either screws onto the front end of the nozzle body or is an integral part of it. Temperature control channels incorporated in the nozzle body permit heating and cooling up to the front of the nozzle.