Electric-powered cutting machine with blade holding mechanism

1. An electric-powered cutting machine, comprising:

a housing;

a plunger held by the housing and protruding outward therefrom, the plunger being driven to reciprocate;

an operation member rotatably mounted on the housing; and

a blade holding mechanism disposed at a tip end portion of the plunger, the blade holding mechanism detachably attaching a blade to the plunger, the blade comprising a pair of projections,

wherein the blade holding mechanism comprises a blade receiving portion including an engaging portion that engages with the projections of the blade,

wherein the operation member comprises an operation portion and an abutting portion,

wherein the blade holding mechanism comprises a rotating member and a pressing member that urges the rotating member toward a side of the blade,

wherein the abutting portion abuts against the rotating member when the operating member rotates in a direction away from an initial position, the initial position being at a rotation end point, thereby causing the rotating member to rotate against a biasing force of the pressing member,

wherein the blade is detachably attached to the plunger by a rotation of the rotating member,

wherein the abutting portion and the operation portion are disposed at different ends of the operation member with respect to the rotating fulcrum,

wherein the rotating member comprises:

a rotation center around which the rotating member is rotated;

a first end being urged by the pressing member to press the blade; and

a second end that is abutted by the abutting portion,

wherein, when the operation member is rotated in the direction away from the initial position, the rotating member is rotated through a contact between the abutting portion and the second end so that a pressing force applied from the first end to the blade is released, thereby detaching the blade from the plunger,

wherein, when the blade is attached to the blade receiving portion of the blade holding mechanism, the blade is clamped by the blade receiving portion and the first end of the rotating member, and the projections of the blade are engaged with the engaging portion of the blade receiving portion, thereby preventing the blade from moving downward,

wherein, when the operation member is in the initial position, the abutting portion, the rotating fulcrum, and the second end are positioned at one side of a line extending along a side surface of the blade, and the operation portion is positioned at another side of the line, and

wherein, when viewed from the longitudinal direction of the blade, the distance from the operation portion to the rotating fulcrum is more than two times of the distance from the abutting portion to the rotating fulcrum.

2. The electric-powered cutting machine according to claim 1 , wherein the abutting portion of the operation member has a shape such that the abutting portion of the operation member extends substantially parallel to a longitudinal direction of the plunger regardless of a position of the plunger where the plunger has a reciprocating motion, so that the abutting portion abuts against the rotating member.

3. The electric-powered cutting machine according to claim 1 , wherein the operation member is biased by the pressing member.

4. The electric-powered cutting machine according to claim 1 ,

wherein said first end of the rotating member, which is pressed toward the blade receiving portion by the pressing member, has a shape which can be placed parallel to the blade receiving portion.

5. The electric-powered cutting machine according to claim 4 ,

wherein said first end of the rotating member comprises a hemispherical convex portion in a place corresponding to a middle portion of a groove formed in the blade receiving portion.

6. The electric-powered cutting machine according to claim 5 , wherein the convex portion protrudes toward the groove to serve as a blade pressing portion.

7. The electric-powered cutting machine according to claim 5 ,

wherein an attachment portion of the blade engages with the groove of the blade receiving portion before the blade attaches to the plunger.

8. The electric-powered cutting machine according to claim 4 ,

wherein the rotation center of the rotating member is located on an extended line of the blade receiving portion, and

wherein said first end of the rotating member is placed parallel to the blade receiving portion.

9. The electric-powered cutting machine according to claim 4 ,

wherein said first end of the rotating member is positioned between an upper face and a bottom face of the blade holding mechanism, and

wherein said second end of the rotating member has a shape which elongates to separate from the blade receiving portion or radially outwardly separates from the plunger.

10. The electric-powered cutting machine according to claim 4 ,

wherein a curved surface of the abutting portion causes the rotating member to rotate against the biasing force of the pressing member.

11. The electric-powered cutting machine according to claim 4 , wherein a projecting member is disposed on the second end of the rotating member,

wherein when the operation member rotates for detaching the blade, the projecting portion causes the blade to automatically slip off from the blade holding mechanism.

12. The electric-powered cutting machine according to claim 1 ,

wherein said rotation center of the rotating member is positioned more rearwardly in a cutting direction than a center of the plunger so that during an operation of attaching or detaching the blade, the plunger can rock in a direction along which the plunger separates from a roller that is provided for abutting against the blade.

13. The electric-powered cutting machine according to claim 1 ,

wherein said rotation center of the rotating member is at a position which is separated from an outer periphery of the plunger, and

wherein a place where the pressing member presses the rotating member is set to a vicinity of an end portion of the rotating member.

14. The electric-powered cutting machine according to claim 1 , wherein the line is perpendicular to the longitudinal direction of the blade.

15. The electric-powered cutting machine according to claim 1 , wherein the line extends along a longitudinal side surface in a cross-section of the blade, the cross-section being defined in the longitudinal direction of the blade.

16. An electric-powered cutting machine, comprising:

a housing;

a plunger held by the housing and protruding outwardly therefrom, the plunger being driven to reciprocate;

an operation member rotatably mounted on the housing about a rotating fulcrum of the operation member; and

a blade holding mechanism disposed at a tip end portion of the plunger, the blade holding mechanism detachably attaching a blade to the plunger, the blade comprising a pair of projections,

wherein the blade holding mechanism comprises:

a rotating member capable of rotating, wherein the blade is detachable from the plunger by rotating of the rotating member by applying a leverage thereto; and

a blade receiving portion including an engaging portion that engages with the projections of the blade,

wherein the blade is attachable to the plunger by the rotating member by applying the leverage thereto,

wherein an abutting portion of said operation member and an operation portion of said operation member are disposed at different ends of the operation member with respect to the rotating fulcrum of the operation member,

wherein the rotating member comprises:

a rotation center around which the rotating member is rotated;

a first end being urged by a pressing member to press the blade; and

a second end that is abutted by the abutting portion,

wherein, when the operation member is rotated in a direction away from an initial position, the initial position being at a rotation end point, the rotating member is rotated through a contact between the abutting portion and the second end so that a pressing force applied from the first end to the blade is released, thereby detaching the blade from the plunger,

wherein, when the blade is attached to the blade receiving portion of the blade holding mechanism, the blade is clamped by the blade receiving portion and the first end of the rotating member, and the projections of the blade arc engaged with the engaging portion of the blade receiving portion, thereby preventing the blade from moving downward,

wherein, when the operation member is in the initial position, the abutting portion, a rotating fulcrum of the operation member, and the second end are positioned at one side of a line extending along a side surface of the blade, and the operation portion is positioned at another side of the line, and

wherein, when viewed from a longitudinal direction of the blade, a distance from the operation portion to the rotating fulcrum is more than two times of a distance from the abutting portion to the rotating fulcrum.

17. The electric-powered cutting machine according to claim 16 , wherein the line is perpendicular to the longitudinal direction of the blade.