Friction stir welding apparatus

1. A friction stir welding apparatus which performs friction stir welding on a work piece by bringing a tool into contact with a surface of the work piece and rotating the tool about the longitudinal axis of the tool and moving the tool relative to the work piece, the friction stir welding apparatus comprising:

a main body for holding the tool such that the main body moves with the tool relative to the work piece;

a hot air and cool air separating unit disposed at the main body and which separates a supplied gas into hot air hotter than the gas and cool air cooler than the gas in a tube portion and ejects the cool air from a first end of the tube portion and ejects hot air from a second end of the tube portion;

a cool air passage extending from the first end of the tube portion for conveying the cool air in a direction from the main body toward the work piece; and

a hot air passage extending from the second end of the tube portion for conveying the hot air in a direction from the main body toward the work piece,

wherein the hot air passage has a hot air opening at a front end of the hot air passage, the hot air opening being disposed on a front side of the main body and arranged to direct the hot air to the surface of the workpiece,

wherein the cool air passage has a cool air opening at a front end of the cool air passage, the cool air opening being disposed on a rear side of the main body and arranged to direct the cool air to the surface of the workpiece, and

wherein the front side of the main body and the rear side of the main body are opposed to each other in a lateral direction perpendicular to the longitudinal axis of the tool, and the hot air opening is disposed on an opposite side of the main body from the cool air opening in the lateral direction.

2. The friction stir welding apparatus of claim 1 , wherein the hot air and cool air separating unit includes

a vortex flow generating portion which is connected to the first end of the tube portion and rotates the gas supplied from the outside in a vortex shape so as to be sent to the second end side inside the tube portion,

a cool air ejection port capable of ejecting the cool air at the first end of the tube portion,

a hot air ejection port capable of ejecting the hot air at the second end of the tube portion,

a pressure adjusting valve which is capable of adjusting the pressure of the gas supplied into the vortex flow generating portion, and

a flow rate adjusting valve which is capable of adjusting the flow rate of the hot air ejected from the hot air ejection port.

3. The friction stir welding apparatus of claim 2 , further comprising:

a torque detecting unit which detects a rotational torque about the axis of the tool; and

a first control device which controls at least one of the pressure adjusting valve and the flow rate adjusting valve on the basis of the value of the rotational torque detected by the torque detecting unit.

4. The friction stir welding apparatus of claim 3 , further comprising:

a reaction force detecting unit which detects a tool reaction force in the direction along the axis and exerted on the tool from the work piece; and

a second control device which controls at least one of the pressure adjusting valve and the flow rate adjusting valve on the basis of the value of the tool reaction force detected by the reaction force detecting unit.

5. The friction stir welding apparatus of claim 2 , further comprising:

a reaction force detecting unit which detects a tool reaction force in the direction along the axis and exerted on the tool from the work piece; and

a control device which controls at least one of the pressure adjusting valve and the flow rate adjusting valve on the basis of the value of the tool reaction force detected by the reaction force detecting unit.

6. A friction stir welding apparatus which performs friction stir welding on a work piece by bringing a tool into contact with a surface of the work piece and rotating the tool about the longitudinal axis of the tool and moving the tool relative to the work piece, the friction stir welding apparatus comprising:

a main body for holding the tool such that a longitudinal axis of the main body is parallel to the longitudinal axis of the tool and the main body moves with the tool relative to the work piece;

a hot air and cool air separating unit disposed at the main body and which separates a supplied gas into hot air hotter than the gas and cool air cooler than the gas in a tube portion and ejects the cool air from a first end of the tube portion and ejects hot air from a second end of the tube portion, the tube portion being connected to the main body such that the tube portion and the main body move together in a movement direction relative to the work piece;

a cool air passage extending from the first end of the tube portion for conveying the cool air in a direction from the main body toward the work piece; and

a hot air passage extending from the second end of the tube portion for conveying the hot air in a direction from the main body toward the work piece;

wherein the hot air passage has a hot air opening, the hot air opening being disposed on a front side of the main body and arranged to direct the hot air to the surface of the workpiece at the front side of the main body,

wherein the cool air passage has a cool air opening, the cool air opening being disposed on a rear side of the main body and arranged to direct the cool air to the surface of the workpiece at the rear side of the main body, and

wherein the front side of the main body and the rear side of the main body are opposed to each other in a lateral direction perpendicular to the longitudinal axis of the main body, and the hot air opening is disposed on an opposite side of the main body from the cool air opening in the lateral direction.

7. The friction stir welding apparatus of claim 6 , wherein the hot air and cool air separating unit includes

a vortex flow generating portion which is connected to the first end of the tube portion and rotates the gas supplied from the outside in a vortex shape so as to be sent to the second end side inside the tube portion,

a cool air ejection port capable of ejecting the cool air at the first end of the tube portion,

a hot air ejection port capable of ejecting the hot air at the second end of the tube portion,

a pressure adjusting valve which is capable of adjusting the pressure of the gas supplied into the vortex flow generating portion, and

a flow rate adjusting valve which is capable of adjusting the flow rate of the hot air ejected from the hot air ejection port.

8. The friction stir welding apparatus of claim 7 , further comprising:

a torque detecting unit which detects a rotational torque about the axis of the tool; and

a first control device which controls at least one of the pressure adjusting valve and the flow rate adjusting valve on the basis of the value of the rotational torque detected by the torque detecting unit.

9. The friction stir welding apparatus of claim 8 , further comprising:

a reaction force detecting unit which detects a tool reaction force in the direction along the axis and exerted on the tool from the work piece; and

a second control device which controls at least one of the pressure adjusting valve and the flow rate adjusting valve on the basis of the value of the tool reaction force detected by the reaction force detecting unit.

10. The friction stir welding apparatus of claim 7 , further comprising:

a reaction force detecting unit which detects a tool reaction force in the direction along the axis and exerted on the tool from the work piece; and

a control device which controls at least one of the pressure adjusting valve and the flow rate adjusting valve on the basis of the value of the tool reaction force detected by the reaction force detecting unit.