Abstract
The introduction of FMS (Flexible Manufacturing System) in machining of large-size pistons (greater than outer diameter 170 mm) has been desired, because various shapes are demanded and moreover the production lot size is small. The automation in FMS construction is essential, but in large-size pistons this is very difficult because the following problems have to be overcome: (1) The integration of various operations for effective floor space utilization. (2) The robot loader with the ability of accurate positioning as well as heavy movable load carrying capacity is demanded, because the positioning accuracy is necessary to the same degree of small (or middle)-size piston. (3) Measurement after every operation is essential to prevent the production of defective pistons, because the unit cost of the large-size piston is very high. (4) The dimension of the outer diameter in the machining of large-size pistons should be automatically controlled, but it has been dependent on the worker's skill owing to the complicated shape and its variety. The FMS construction for large-size piston machining was completed by applying the following representative techniques: (1) Integrated system of multiple operations for effective floor space utilization. (2) Automatic conveyor system consisting of robust robot loaders with accurate positioning and AGV (Automated Guided Vehicle). (3) Inner cooling pipe sensing by the ultrasonic inspection instrument and measuring system. (4) Development of non-circular outer diameter finishing machine being capable of machining complicated profiles and any type of piston. The advantage of constructed FMS is that the productivity increases to about 3 times as compared to the conventional manual line.
