Watch with a rigid casing-up, and casing-up method

A watch with a rigid casing-up, comprising:

• a middle;
• a bottom;
• a movement;
• and
• a casing-up ring in contact with the middle;
• in which:
• the casing-up ring has an inner peripheral face, of which the profile comprises at least one zone Z, the tangent (T) to which forms a non-zero angle (α) of less than 90 degrees with the axis (X) passing through the center of the movement and perpendicular to the plane formed by the latter;
• the movement is integral with an outer peripheral face, of which the profile comprises at least one zone Z′, the tangent (T′) to which forms a non-zero angle (α′) of less than 90 degrees with the said axis (X);
• the said inner and outer peripheral faces being in contact with each other in the Z and Z′ regions thereof,
• wherein the watch also comprises a tightening element provided for exerting pressure on the casing-up ring or the movement.