Blade change mechanism for power tool

1. A blade replacement apparatus for replacing blades connected by a bolt, the bolt extending along a first axis, comprising:

a nut that fits the bolt to fix the blade;

a nut loosening/tightening member;

a locking member; and

an operating member, one of the nut loosening/tightening member and the operating member is provided with a first matching portion, and the locking member is provided with a second matching portion;

wherein the operating member is movable between an operating position and a non-operating position, the operating member allowing a user to perform an operation by hand without using any instruments;

wherein when the operating member is in the non-operating position, the first matching portion engages with the second matching portion, and the rotation of the nut loosening/tightening member around the first axis is obstructed by the locking member; and

wherein when the operating member is in the operating position, the first matching portion is disengaged from the second matching portion, and the rotation of the nut loosening/tightening member around the first axis tightens or loosens the nut,

wherein the operating member is pivotally connected to the nut loosening/tightening member, so that the operating member is rotatable around a second axis, and the second axis is not parallel to the first axis.

2. The blade replacement apparatus as claimed in claim 1 , wherein the nut and the nut loosening/tightening member are integrally formed.

3. The blade replacement apparatus as claimed in claim 1 , wherein the nut and the nut loosening/tightening member are components independent of each other, the nut loosening/tightening member defines a cavity that is in a shape fit with the nut, and when the operating member is in the operating position, at least a part of the nut is located in the cavity.

4. The blade replacement apparatus as claimed in claim 1 , further comprising a biasing member, wherein when the operating member is not operated, a biasing force generated by the biasing member keeps the operating member in the non-operating position.

5. The blade replacement apparatus as claimed in claim 4 , wherein the operating member comprises a grip portion and a biasing action portion, which are respectively located on either side of the second axis, and the biasing force is applied to the biasing action portion; preferably, at least a part of the biasing member is accommodated in the nut loosening/tightening member.

6. The blade replacement apparatus as claimed in claim 5 , wherein a biasing member holding body is provided between the biasing member and the biasing action portion, one end of the biasing member holding body is connected with the biasing member, and the other end is in contact with the biasing action portion; preferably, at the other end of the biasing member holding body, a hemispherical contact portion is formed, which is in contact with a recessed biasing portion on the operating member.

7. The blade replacement apparatus as claimed in claim 1 , wherein the locking member is located between the nut loosening/tightening member and the operating member, and the first matching portion is formed on the operating member.

8. The blade replacement apparatus as claimed in claim 7 , wherein the first fitting portion comprises at least one protrusion formed on the surface of the operating member, and the second matching portion comprises at least one groove or hole formed on the locking member; when the operating member is in the non-operating position, the at least one protrusion is located in the at least one groove or hole.

9. The blade replacement apparatus as claimed in claim 8 , wherein the locking member is formed as an annular member, which surrounds at least a part of the nut loosening/tightening member, and the second matching portion comprises at least one groove formed on the inner edge or the outer edge of the annular member.

10. The blade replacement apparatus as claimed in claim 1 , wherein the operating member and the nut loosening/tightening member are formed integrally or connected such that the two are not rotatable relative to each other, and the operating member is movable along the first axis as operated by a user to move into or out of the operating position.

11. The blade replacement apparatus as claimed in claim 10 , further comprising a biasing member that applies a biasing force to the operating member or the nut loosening/tightening member, wherein when the operating member is not operated, a biasing force generated by the biasing member keeps the operating member in the non-operating position.