Smooth timepiece bearing
AssigneeETA SA Manufacture Horlogere Suisse
InventorsLaurent Kaelin, Julien Moulin
Life of this patent
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Abstract
Smooth timepiece bearing (1). It includes a core (5) of plastic material injected into a cavity of revolution (4) of an outer cage (3). It also includes an inner cage (2) contained within said cavity (4) and said core (5) is injected between said inner cage (2) and said outer cage (3). Said core (5) can move with an operating clearance relative to said outer cage (3) and cannot be removed from said outer cage (3) and can move with an operating clearance relative to said inner cage (2), and cannot be removed from said inner cage (2).
Claims20
A smooth timepiece bearing, characterised in that it includes a core made of plastic material injected into a cavity of revolution comprised in an outer cage, and in that said core can move with a permanent, residual operating clearance relative to said outer cage, and cannot be removed from said outer cage.
The method of manufacturing a smooth timepiece bearing, wherein the following steps are performed:
- an outer cage, which is intended to be incorporated in said smooth bearing and which comprises a cavity of revolution about an axis of revolution, is prepared;
- said cavity is used as an injection or casting chamber;
- plastic material is injected or cast in said chamber to form a core delimited by said cavity;
- the conditions for thermal or crystal shrinkage of said plastic material are ensured to limit said shrinkage to a range of between 2.0% and 3.0%;
- said plastic material is allowed to shrink completely before said smooth bearing is used;
Dependencies are inferred from the claim text.