Pre-tightening disc spring, assembly comprising the pre-tightening disc spring, and method for manufacturing the pre-tightening disc spring

A pre-tightening disc spring, comprising:

• a disc-shaped body which is integrally formed, the disc-shaped body being formed with a central hole, the disc-shaped body having a first contact side and a second contact side which are opposite to each other in a thickness direction of the disc-shaped body, the disc-shaped body being a rotation solid formed by rotating a radial section around a central rotation axis by 360 degrees, the central rotation axis coinciding with a central axis of the central hole, the radial section having a first line segment and an opposing second line segment, the first contact side being defined by rotating the first line segment, the second contact side being defined by rotating the second line segment, a medium-diameter axis being defined to passing a mid-point of the second line segment and extending normally relative to the second line segment, the radial section being mirror-symmetrical relative to the medium-diameter axis, the medium-diameter axis being non-parallel to the central rotation axis, the first line segment being arc-shaped, a point of intersection of the medium-diameter axis and the first line segment being a point such that a vertical distance measured from this point to a straight line segment connecting between both terminals of the second line segment is the greatest one among vertical distances measured from all points in the first line segment to the same straight line segment, wherein in a free state of the pre-tightening disc spring, a minimum thickness between the first and second contact sides of the disc-shaped body is greater than ¾ of a free height of the disc-shaped body and greater than 1/12 of a free outer diameter of the disc-shaped body.