| 摘要 |
PROBLEM TO BE SOLVED: To greatly improve the operability and to prevent the damage of the peripheral edge of the coupling part of a reverse flow ring or a nozzle by so constituting a reverse flow preventing mechanism as to be completely discharged out of a heating cylinder when the nozzle is removed. SOLUTION: A reverse flow preventing ring 6 is always brought into contact with the inner surface of a nozzle 1 or a heating cylinder 3. When there is a step on the connecting part of the coupling part of the cylinder to the nozzle, the outer periphery of the ring is engaged with the step by the movement of metering or injecting to disturb the smooth movement of the ring or damage the peripheral edge of the coupling part of the ring or the nozzle. In order to prevent the engagement with the step, the outer peripheral edges 8, 9 of both the surfaces of the ring 6 opposite to the screw head and the screw body 2 are curved or chamfered thereby to be able to smoothly move the ring 6. |
