Method for cutting watch crystals

Patent metadata

Field	Value
Publication number	US-11054790-B2
Application number	US-201816104238-A
Country	US
Kind code	B2
Filing date	Aug 17, 2018
Priority date	Oct 16, 2017
Publication date	Jul 6, 2021
Grant date	Jul 6, 2021

Abstract

A method for cutting watch crystals along a plurality of contours in a plate of transparent material includes forming a first cut line or kerf to form a first chamfer for each of the crystals of the plate and marking at least one machined recess on a first side of the plate, turning the plate over and marking at least one of the position of the first chamfer and the position of the at least one machined recess, forming a second cut line or kerf to form a second chamfer for each of the crystals on a second side of the plate, and separating the crystals by machining through the plate at each of the contours to form edges of the crystals.

First claim

What is claimed is:

1. A method for cutting watch crystals along a plurality of contours in a plate of transparent material, comprising:
first step: forming on a first side of the plate, a first cut line or kerf on at least the inside of one of the contours, to form a first chamfer, for each of the crystals to be made from the plate, and making at least one machined recess on the first side of the plate;
second step: turning over the plate and marking at least one of the position of the first chamfer and the position of the at least one machined recess;
third step: forming on a second side of the plate, opposite to the first side, a second cut line or kerf on at least the inside of the one of the contours, to form a second chamfer, in alignment with the first cut line and the first chamfer, for each of the crystals to be made from the plate; and
fourth step: separating the crystals from a skeleton of the plate by machining through the plate at each of the contours to form edges of the crystals.

2. The method according to claim 1 , wherein, during at least one of the first step and the third step, there is used one of a grinding wheel and a bell tool whose profile corresponds to the first chamfer or the second chamfer to be formed, driven in rotation and plunged straight onto the plate, if the one of the contours is circular.

3. The method according to claim 1 , wherein, during at least one of the first step and the third step, there is used one of a grinding wheel and a bell tool driven in rotation and effecting multi-axis contouring along the one of the contours, with the axis of rotation of one of the grinding wheel and the bell tool moving through space perpendicularly to a plane locally tangent to the first chamfer or the second chamfer to be formed.

4. The method according to claim 1 , wherein, during at least one of the first step and the third step, there is used a shank boring tool mounted on a boring head, driven in rotation and plunged straight onto the plate, when the one of the contours is circular.

5. The method according to claim 1 , wherein, during at least one of the first step and the third step, there is used a shank boring tool driven in rotation and effecting multi-axis contouring along the one of the contours, with the axis of rotation of a boring head carrying the shank boring tool moving through space perpendicularly to the plane locally tangent to the first chamfer or the second chamfer to be formed.

6. The method according to claim 1 , wherein
during the second step, the plate is placed on a tool including at least one relief portion arranged to cooperate with the at least one machined recess to position the plate in a unique position, and
the plate is immobilized on the tool.

7. The method according to claim 6 , wherein the at least one machined recess, and the at least one corresponding relief portion, each includes a mutually complementary conical contact surface.

8. The method according to claim 1 , wherein, during the fourth step the crystals are separated from the skeleton by a machining operation along each of the contours performed one of by laser or water jet cutting, and by plunge grinding if each of the contours is circular, with one of a grinding wheel and a bell tool with a straight internal profile driven in rotation and plunged straight onto the plate.

9. The method according to claim 1 , wherein, during at least one of the first step and the third step, the first cut line or the second cut line is machined with a grinding wheel which is cooled in a sharpening station disposed in immediate proximity to the plate.

10. The method according to claim 1 , wherein,
during at least one of the first step and the third step, a surface condition of the first chamfer or the second chamfer is checked once the first chamfer or the second chamfer is formed, and
when one of a predefined roughness threshold and a transparency threshold has been breached, one of a grinding wheel and a tool is one of changed and sharpened in a sharpening station disposed in immediate proximity to the plate.

11. The method according to claim 1 , wherein
a plurality of the crystals is made from a same plate, and
from the same plate, crystals with different contours are made to minimize waste of material in the skeleton.

12. The method according to claim 1 , wherein, during at least one of the first step, the third step, and the fourth step, a work area is lubricated with at least one of air and a liquid to evacuate machining waste.

13. The method according to claim 1 , wherein, during at least one of the first step, the third step, and the fourth step, the plate is immersed in a liquid fluid to which a current is imparted to evacuate machining waste.

Assignees

• Swatch Group Res & Dev Ltd

Inventors

• Bazin Jean-Luc
• Gunn-Sechehaye Martin

Classifications

• C03B33/10

  Glass-cutting tools, e.g. scoring tools · CPC title

• C03B33/023

  the sheet {or ribbon} being in a horizontal position · CPC title

• C03B33/04 Primary

  Cutting or splitting in curves, especially for making spectacle lenses · CPC title

• G04B39/004

  from a material other than glass · CPC title

• B28D7/043

  the supporting or holding device being angularly adjustable · CPC title