5. MANUFACTURING FACILITIES FOR HIGH-PERFORMANCE PROPELLERS
The high-performance propellers developed by us such as PAI propeller and highly skewed propeller introduced as above have rather complicated configurations of blade section and blade contour compared with those of conventional propellers. It will therefore extremely be difficult for these propellers to be manufactured to the drawings. For making these high-performance propellers feasible for practical use, the superior manufacturing technology taking advantage of computers will be requisite in addition to the improvements and developments of designing/analyzing technology. We herewith accordingly wish to introduce our most advanced computerized system for the propeller manufacturing developed by ourselves.
5-1. NC MILLING MACHINES
In the past regretfully there was no other way than that the propeller blades of complicated 3-dimensional configuration shall manually be processed using special gauges, and hand grinders controllable only by experienced/skilled workers. The dimensional deviations and the rougher surface of those propellers caused by non-uniformity of the conducted manual work were directly the causes for the deterioration of propeller efficiency, and it was consequently difficult for the intended high-performance of propeller offered by the designing or technological improvement to straight be reflected onto the product quality of propeller.
We Nakashima Propeller Company set about the introduction of NC machines in 1973, and the propeller blades are machined by a group of NC machines, whereby it was made possible for such propellers as our PAI propellers and highly skewed propellers with remarkably complicated configurations to be machined in further stringent accordance with the propeller drawings with finer accuracies. The NC machines also contribute greatly to the improvement of productivity. NC milling machining system has been constructed, with a group of NC milling machines for smaller-sized propellers, medium-sized propellers, and larger-sized propellers installed specifically for each different size.
Photograph 6 shows the appearance of the CNC blade milling machine of 5-axis simultaneous control for large-sized propellers, where CAD/CAM systems specializing in propeller manufacture operated by host computer automatically processing the propeller manufacturing drawings and NC machining data, besides, as-cast material is automatically measured for automatically deciding appropriate milling allowances.
Two units of the NC blade milling machines for medium-sized propellers (Photograph 7) are in operation, both being of 5-axis simultaneous control. FMC system (Flexible Manufacturing CNC milling machine for medium-sized propellers) is adopted, excluding usually required huge amount of NC tapes by linking on line with the milling machine, computerized for exclusive use, and host computer, whereby we are well competent to cope with the production of a wide variety of kinds/types of propellers even for a smaller quantity. Besides, the blade root and boss also can be machined by them.
