| 摘要 |
A nozzle shut-off valve for injection molding machine for plastic material, especially thermoplastic material, has two pneumatic cylinder-and-plunger units. One such unit has its plunger mounted to reciprocate so as to block the passageway of the plastics through the nozzle. The first such plunger and cylinder unit is provided with a pilot passage in the valve nozzle so that the pressure of molten plastic can be used to open it. The second such unit is much smaller diameter and has its plunger mounted to block the pilot passage so that the second unit in effect becomes a pilot valve and controls the application of fluid pressure through the pilot passage to the first unit plunger or blocking plunger.
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