1906年，它们可以在有排孔的传送带上被压制生产，一次十二个，此后它变得更便宜。

It became cheaper still when, after 1906, they could be extruded by perforated conveyor belts a dozen at a time.

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钻头体中有个孔作为导管在相当大的压力下将冷却液传送到钻头顶端。

A hole in the body ACTS as a conduit to transmit coolant under considerable pressure to the tip of the drill.

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公母端内孔平齐的设计使得油气在传送过程中不会发生紊流现象，减小传输阻力。

The design of flush inner holes at male and female ends enables the oil gas not to be subject to turbulence in the transmission process, and reduces the transmission resistance.

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