腕時計リュウズの鍛造加工システムの開発

抄録

The forge processing system which consists of cold multistage forging, tapping and formrolling has been developed. A wristwatch crown, which is small and complicated with a groove, can be formed with the forge processing system into its final shape in a fairly short time which is about 1/15 of the time required in a conventional cutting process. The cold multistage forging is accomplished in six processes including shearing of a wire, upsetting of a crown head and forward extrusion. The tapping is conducted to the forged crown after the annealing. The groove can be formed with form rolling using the flat tools in the stem of a crown. The crown manufactured on the forge processing system can be finished only in the barrel polishing to smooth surface without large defects. Mass-production and practical application of a cheap crown may now be realized as a result of this processing system development.