| 摘要 |
The invention provides apparatus suitable for use in continuous transfer of workpieces through a region of reduced pressure in which some operation is to be performed on each workpiece in turn, being particularly, but not exclusively, suitable for electron beam welding. The apparatus comprises a sealed chamber, to constitute the region of reduced pressure, and a passageway extending therethrough, with means defining a series of compartments for containing individual workpieces, the compartments being movable in succession along the passageway and through an operating station in the sealed chamber where the interior of each compartment in turn is exposed to the interior of the sealed chamber for the performance of an operation on a workpiece carried in the compartment. Each compartment is arranged to be sealed from adjacent compartments when it is upstream or downstream of the operating station so that the pressure in each compartment in turn can be reduced to a level intermediate atmospheric pressure and the reduced pressure in the sealed chamber before that compartment reaches the operation station, thereby avoiding excessive fluctuations in the pressure in the sealed chamber which might otherwise occur. Conveniently, but not essentially, the pressure in each compartment in turn is partially raised downstream of the operating station before it arrives at an output end of the passageway.
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