| 摘要 |
A stationary platen of an injection-molding machine, carrying a mold portion with a sprue leading to one or more cavities, is connected by a set of metallic tie bars with a fixed part of the machine frame containing the mold drive and is limitedly slidable on the machine bed to an extent corresponding to the stretch of the tie bars under a mold-clamping force exerted by that drive upon another platen moving along the tie bars. An injection unit behind the stationary platen has a precompression chamber which communicates with a channel leading to an injection nozzle, this nozzle being received in a cutout of that platen and confronting the sprue through the head of a hollow gating plunger slidable in the nozzle orifice. The injection unit is mounted on a carriage arrestable in a position in which the head of the forwardly biased plunger, whose tail blocks the nozzle orifice, closely approaches the sprue of the stationary mold portion prior to closure of the mold by the approach of another mold portion on the movable platen. With the mold closed, and upon an elastic stretching of the tie bars by the exerted mold-clamping force, the plunger head is repressed by slightly less than 1 mm to unblock the nozzle orifice and let the precompressed mass in the injection unit enter the cavity or cavities thereof.
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