Press-fitting auxiliary tool, pressure head and press-in device

The utility model discloses a press-fitting auxiliary tool, a pressing head and a press-in device. The open lining has a first state and a second state, the first outer diameter of the open lining in the first state is larger than the second outer diameter of the open lining in the second state, and the press-fitting auxiliary tool comprises a main body which comprises a first surface and a second surface which are oppositely arranged in the first direction; the guide hole extends in the first direction and is communicated with the first surface and the second surface, the inner wall surface of the guide hole is provided with a transition part, the transition part is provided with a first opening and a second opening which are oppositely arranged in the first direction, and the inner diameter of the first opening is larger than or equal to the first outer diameter; the inner diameter of the second opening is smaller than the first outer diameter and larger than or equal to the second outer diameter, and the i