Hinge assembly and opening and closing device

An opening and closing device, comprising:

• a cabinet, having an opening;
• and
• a door body, hinged to the opening of the cabinet through a hinge assembly, comprising:
• a first matching member, provided with a first curved surface and a second curved surface at one end of the first matching member;
• a second matching member, provided with a third curved surface and a fourth curved surface at one end of the second matching member;
• wherein the hinge assembly has a first state and a second state, and the first matching member and the second matching member are rotatable relative to each other around a first axis to be switchable between the first state and the second state;
• and in the first state, the first curved surface abuts against and is matched with the third curved surface to make the first matching member and the second matching member have a first acting force under an axial force;
• and in the second state, the second curved surface abuts against and is matched with the fourth curved surface to make the first matching member and the second matching member have a second acting force under the axial force;
• and the first acting force and the second acting force have opposite directions.