Binding machine

1. A binding machine comprising:

a wire feeding unit configured to feed a wire;

a curl forming unit configured to form a path along which the wire fed by the wire feeding unit is to be wound around a to-be-bound object;

a butting part against which the to-be-bound object is to be butted;

a cutting unit configured to cut the wire wound on the to-be-bound object;

a binding unit configured to twist the wire wound on the to-be-bound object and cut by the cutting unit, the binding unit comprising:

a rotary shaft,

a wire engaging body configured to move in an axis direction of the rotary shaft, to engage the wire and to twist the wire with rotating together with the rotary shaft, and

a spring for urging the rotary shaft in a direction in which the wire engaging body gets away from the butting part along the axis direction of the rotary shaft, and for regulating an axial position of the rotary shaft; and

a tension applying part, separate from the spring, configured to apply tension to the wire to be cut at the cutting unit with a force higher than a reaction force of the wire in a loosening direction of the wire wound on the to-be-bound object.

2. The binding machine according to claim 1 , wherein the tension applying part is configured to maintain the tension applied to the wire by an operation of reversely feeding the wire and winding the wire on the to-be-bound object.

3. The binding machine according to claim 1 ,

wherein the tension applying part is configured to urge at least one of the wire engaging body and the rotary shaft in a direction in which the tension applying part maintains the tension applied to the wire by an operation of reversely feeding the wire and winding the wire on the to-be-bound object.

4. The binding machine according to claim 3 , wherein in an operation area where the wire engaging body moves in the axis direction of the rotary shaft and twists the wire with rotating together with the rotary shaft, the tension applied to the wire by the tension applying part is equal to or larger than 10% and equal to or smaller than 50% with respect to a maximum tensile load of the wire.

5. The binding machine according to claim 3 , wherein the tension applying part includes a tension applying spring configured to urge the wire engaging body in a direction away from the butting part along the axis direction of the rotary shaft.

6. The binding machine according to claim 5 , wherein the wire engaging body comprises a hook configured to engage the wire by an opening/closing operation and a sleeve configured to open/close the hook, and

wherein the tension applying part is a coil spring and is provided on an outer side of the sleeve.

7. The binding machine according to claim 1 , wherein the tension applying part is configured to apply the tension to the wire after cutting the wire by the cutting unit until twisting the wire by the binding unit.

8. The binding machine according to claim 1 , wherein the tension applying part is configured to urge the to-be-bound object butted against the butting part and the binding unit engaging the wire in a direction getting away from each other.

9. The binding machine according to claim 1 , wherein the tension applying part comprises: a first tension applying part configured to urge at least one of the wire engaging body and the rotary shaft in a direction which maintains the tension applied to the wire by an operation of reversely feeding the wire and winding the wire on the to-be-bound object, and a second tension applying part configured to urge the to-be-bound object butted against the butting part and the binding unit engaging the wire in a direction getting away from each other.