Shaft alignment of scroll compressors

Vertical scroll compressors can be built either with a pre-assembly of a motor-compressor, to be integrated into a hermetic shell, or with the direct assembly of parts inside the shell. In the first case, the shaft alignment is already set by the mechanical parts geometries and tolerances of the pre-assembly. In the second case, the shaft position is defined not only by the parameters of a mechanical assembly, but also by the behaviour of the components during the mounting process, e.g. the deformation of the material after the welding of the upper shell. This is why it is necessary to adapt the alignment of the shaft for a compressor under construction on the assembly line. Each machine needs particular settings. The process consists of several steps, which include the primary assembly of the rotating parts in the shell, the scanning for the ideal position of the shaft, the immobilization of the shaft and lower bearing in the optimal position. This design eradicates unnecessary machining precision for assembly requirements; the precise parts are reserved for the gas compression. This solution decreases costs, keeping excellent performance in efficiency, noise and reliability. This article gives details about the equipment and process.