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Laser turning of watch component shaft

IP.com Disclosure Number: IPCOM000256526D
Publication Date: 2018-Dec-06
Document File: 2 page(s) / 221K

Publishing Venue

The IP.com Prior Art Database

Abstract

Laser turning of simplified escapement shafts, including pivots, in Nivaflex® metallic alloy (see figure 1) has been demonstrated. This grade is known for its low machinability that leads to rapid wear of carbide cutting tools. All dimensional features of the shaft, including pivots, are well performed with extremely low dispersion. The quality surface right after laser turning was measured slightly worse than the required specifications for shaft produced by standard turning plus a cold rolling. In order to obtain a surface quality equivalent to finished cold rolled pivots in 20AP, a simple tumbler polishing was performed on laser turned shafts. Final rendering was particularly good with a surface roughness even better than rolled part and dimensional features still inside the accepted tolerances.

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PRECISION LASER TURNING Viable alternatives to conventional machining processes are needed in the watch industry in order to integrate new materials that feature excellent magnetic and corrosion resistance as well as high mechanical strength but that exhibit low machinability behavior. Replacing 20AP steel by a low machinability material can lead to very high production costs, since carbide tool consumption would drastically increases and chips disposal would be hard to ensure.

Previous studies allowed to identify a new process development based on a 5 axis CNC machine equipped with an ultrashort pulse laser (USP) that produces an uniform laser spot as small as 25 µm. An extremely high amount of energy is applied to the work piece for a short time. Melting or thermal changes don't occur because the material is vaporised instantly. Additionally, the laser is put into rotation with so-called trepanning optics: different corner radii on the part can be manufactured by automatically changing the rotation diameter and incidence angle. This set up allows very good control of the process and allows for manufacturing within a tight tolerance range.

Laser turning of simplified escapement shafts, including pivots, in Nivaflex® metallic alloy (see figure 1) has been demonstrated. This grade is known for its low machinability that leads to rapid wear of carbide cutting tools. All dimensional features of the shaft, including pivots, are well performed with extremely low dispersion. The q...