Oscillating winding mass provided with a rotating decorative element for automatic movement of a timepiece

1 . An oscillating winding mass ( 1 ) for a movement of a timepiece, said oscillating winding mass ( 1 ) being intended to be rotatably mounted on an axis of the movement, comprising a main element ( 2 ) and a decorative element ( 10 ), a part of the winding mass ( 1 ) forming a heavy part ( 3 ) allowing the oscillation of the mass ( 1 ) in response to the movement of the timepiece and to the force of gravity, the decorative element ( 10 ) being mechanically linked to the main element ( 2 ), the decorative element ( 10 ) being rotatably mounted on the main element ( 2 ) by a ball bearing ( 8 ) of the main element ( 2 ) to allow the decorative element ( 10 ) to rotate with contact of a portion of the decorative element ( 10 ) along balls ( 9 ) of the ball bearing ( 8 ) within the main element ( 2 ), the main element ( 2 ) including an opening ( 6 ) wherein the decorative element ( 10 ) is arranged, the main element ( 2 ) being made of amorphous metal,

wherein the ball bearing ( 8 ) is arranged on the main element ( 2 ),

wherein the ball bearing ( 8 ) is disposed in an internal face ( 7 ) of the opening ( 6 ),

wherein the internal face ( 7 ) of the opening ( 6 ) includes rails ( 13 , 14 ) for retaining the decorative element ( 10 ) in the opening ( 6 ), and the rails ( 13 , 14 ) are circular,

wherein the main element ( 2 ) overall and the decorative element ( 10 ), overall and within the opening ( 6 ) of the main element ( 2 ), both comprise anchor shapes, with the decorative element ( 10 ) being a smaller anchor shape than that of the main element ( 2 ),

the anchor shapes, of both the main element ( 2 ) and the decorative element ( 10 ), comprise a neck and an arc, the neck being attached to the arc at an inner circumferential center of the arc, the neck being shaped as a straight segment ( 11 ), and the arc being shaped as a curved segment ( 12 ), and

the arc and the neck of the smaller anchor shape of the decorative element ( 10 ) occupy less than half of a total space of the opening ( 6 ), and an end of the neck of the smaller anchor shape of the decorative element ( 10 ) is centered in the opening ( 6 ).

2 . The winding mass ( 1 ) according to claim 1 , wherein the balls ( 9 ) are distributed angularly in the internal face ( 7 ) of the opening ( 6 ).

3 . The winding mass ( 1 ) according to claim 2 , wherein the balls ( 8 ) are disposed in the mass of the main element ( 2 ).

4 . The winding mass ( 1 ) according to claim 3 , wherein the ball bearing ( 8 ) comprises balls ( 9 ) of which each ball ( 9 ), of the ball bearing ( 8 ), is retained in a housing whose dimensions allow each ball ( 9 ) to rotate while being retained in a substantially predefined position.

5 . The winding mass ( 1 ) according to claim 4 , wherein the housing comprises an orifice ( 15 ) emerging into the opening ( 6 ), so that part of each of the balls ( 9 ) protrudes from the housing into the opening ( 6 ) so as to be able to be in contact with the decorative element ( 10 ).

6 . The winding mass ( 1 ) according to claim 1 , wherein the ball bearing ( 8 ) comprises balls ( 9 ) that are made of ruby.

7 . The winding mass ( 1 ) according to claim 1 , wherein the decorative element ( 10 ) comprises a portion configured to contact balls ( 9 ) of the ball bearing ( 8 ).

8 . The winding mass ( 1 ) according to claim 1 , wherein the decorative element ( 10 ) comprises, entirely, ceramic.

9 . A timepiece including a case formed of a middle part closed by a crystal and an at least partially transparent back and wherein is housed a self-winding timepiece movement, wherein said movement is equipped with the oscillating winding mass ( 1 ) according to claim 1 .

10 . A method for manufacturing a winding mass according to claim 1 , the method comprising the following steps:

a first step wherein ruby balls ( 9 ), the ruby balls ( 9 ) being balls ( 9 ) of the ball bearing ( 8 ), are formed,

a second step wherein the balls ( 9 ) are covered with a metal layer,

a third step wherein the balls ( 9 ) are embedded in an amorphous metal mass of the main element ( 2 ),

a fourth step wherein the metal layer is dissolved by a chemical technique to obtain the ball bearing ( 8 ).