The present machine tool market has no machining centers capable of completely processing
the parts of a 13,000 cc displacement-class engine (1,000 mm in total length), the largest size
offered by domestic truck/bus manufacturers. It is, therefore, necessary to build a dedicated line
equipped with special purpose machines, and existing processing lines were poor in terms of
benefit-cost ratio and are inflexible. Crank-hole drilling on a cylinder block as a key engine part
requires the long tool called a line borer. To meet this requirement, Mitsubishi Heavy Industries,
Ltd. (MHI) developed the M-CM5BG horizontal machining cell with equipment that automatically
replaces long tools of a maximum of 1,350 mm (and stores four tools at one time). Along with a
high-rigidity bed for which the Z-axis stroke of 1,700 mm needed for long tool machining has been
realized by supporting it at three points, the technologies mounted on this machine for
maintainability, automation and labor saving are featured in this paper.
