초록 ▼

The end of a hollow member 10 is abutted against the end of a hollow member 20. The end of a face plate 21 is supported on a protrusion 15. A small-diameter portion 52 of a rotary tool 50 is inserted into the abutted area, and the tool 50 is moved along the abutted region while being rotated in a c

The end of a hollow member 10 is abutted against the end of a hollow member 20. The end of a face plate 21 is supported on a protrusion 15. A small-diameter portion 52 of a rotary tool 50 is inserted into the abutted area, and the tool 50 is moved along the abutted region while being rotated in a clockwise direction as observed from the large-diameter potion 51. Thus, the pressure of mobilized metal is greater on the right side of the axial center of the rotary tool. The thickness of the member from the tip of the inserted small-diameter portion 51 to the hollow areas 10b and 10a is thicker at the right side where the pressure is higher, thus preventing metal from flowing out into the hollow region 10a.

대표청구항 ▼

We claim: 1. A friction stir welding method for welding a first member and a second member, the first member comprising a plate, the plate being provided with a protrusion protruding substantially parallel to said plate from an end portion of said plate and arranged at a displaced position from one

We claim: 1. A friction stir welding method for welding a first member and a second member, the first member comprising a plate, the plate being provided with a protrusion protruding substantially parallel to said plate from an end portion of said plate and arranged at a displaced position from one surface of said plate, said friction stir welding method comprising the steps of: superimposing an end portion of said second member on said protrusion, and abutting said end portion of said second member against the end portion of said plate, thereby providing abutted portions; and friction stir welding the abutted portions using a rotary tool having a small-diameter portion mounted on an end of a large-diameter portion, by inserting said small-diameter portion into a joint between said abutted portions; wherein: the rotary tool is positioned so that when observed along a direction in which said tool moves along said joint during the friction stir welding, a distance from a tip portion of said inserted small-diameter portion to a surface of said first member opposite from said large-diameter portion is greater on the right side of the axial center of said rotary tool than on the left side thereof, said distance from the tip portion of said inserted small-diameter portion to the surface of the first member opposite said large-diameter portion on the right side being sufficiently large to avoid flow-out of material of said first member at the right side; said protrusion extends to said right side of the welding line as seen in the direction of movement of said tool when performing said friction stir welding; and said rotary tool is rotated in a clockwise direction as observed from the large-diameter portion side while being moved along said joint during the friction stir welding. 2. A friction stir welding method according to claim 1, wherein the tip portion of small-diameter portion is inserted into said protrusion when performing said friction stir welding. 3. A friction stir welding method according to claim 1, wherein said small-diameter portion of the rotary tool has a screw thread, the screw thread being a left-hand screw thread. 4. A friction stir welding method for welding a hollow member and a second member, the hollow member comprising two substantially parallel face plates, a connecting plate for connecting said two face plates, a protrusion protruding substantially parallel to one face plate from said connecting plate, and provided at an end portion of said one face plate, and a recessed portion recessed both from the outer side of said one face plate and from the protruded direction of said protrusion at the joint portion joining said one face plate, said connecting plate and said protrusion; said friction stir welding method comprising the steps of: superimposing the end portion of the second member on said recessed portion, while abutting said end portion of said second member against the end portion of said one face plate, providing abutted portions having a joint therebetween; and friction stir welding the abutted portions using a rotary tool having a small-diameter portion mounted on an end of a large-diameter portion, by inserting said small-diameter portion into the joint between said abutted portions and said protrusion; wherein: said protrusion is positioned on a right side of the axial center of said rotary tool as seen when said rotary tool is observed from a direction in which said tool moves along said joint during the friction stir welding; a distance from a tip portion of said inserted small-diameter portion to a surface of said hollow member opposite from said large-diameter portion is greater on the right side of the axial center of said rotary tool having said protrusion than on the left side thereof, when observed from the direction in which said tool moves during the friction stir welding, said distance from the tip portion of said inserted small-diameter portion to the surface of the first member opposite said large-diameter portion on the right side being sufficiently large to avoid flow-out of material of said first member at the right side; and said rotary tool is rotated in a clockwise direction as observed from the large-diameter portion side while being moved along said joint during the friction stir welding. 5. A friction stir welding method according to claim 4, wherein said small-diameter portion of the rotary tool has a screw thread, the screw thread being a left-hand screw thread. 6. A friction stir welding method for welding a first member and a second member, the first member comprising a plate, the plate being provided with a protrusion protruding substantially parallel to said plate from an end portion of said plate and arranged at a displaced position from one surface of said plate, said friction stir welding method comprising the steps of: superimposing an end portion of said second member on said protrusion, while abutting said end portion of said second member against the end portion of said plate, thereby providing abutted portions having a joint therebetween; and friction stir welding the abutted portions using a rotary tool having a small-diameter portion mounted on an end of a large-diameter portion, by inserting said small-diameter portion into the joint between said abutted portions; wherein: the rotary tool is positioned so that when observed along the direction in which said tool moves along said abutted portions during the friction stir welding, a distance from a tip portion of said inserted small-diameter portion to the surface of said first member opposite from said large-diameter portion is greater on the left side of the axial center of said rotary tool than on the right side thereof, said distance from the tip portion of said inserted small-diameter portion to the surface of the first member opposite said large-diameter portion on the left side being sufficiently large to avoid flow-out of material of said first member at the left side; said protrusion extends to said left side as seen in the direction of movement of said tool when performing said friction stir welding; and said rotary tool is rotated In a counter-clockwise direction as observed from the large-diameter portion side while being moved along said abutted portions during the friction stir welding. 7. A friction stir welding method according to claim 6, wherein said small-diameter portion of the rotary tool has a screw thread, the screw thread being a right-hand screw thread. 8. A friction stir welding method according to claim 6, wherein the tip portion of said small-diameter portion is inserted into said protrusion when performing said friction stir welding. 9. A friction stir welding method for welding a hollow member to a second member, the hollow member comprising two substantially parallel face plates, a connecting plate for connecting said two face plates, a protrusion protruding substantially parallel to one face plate from said connecting plate, and a recessed portion recessed both from an outer side of said one face plate and from the protruded direction of said protrusion at a joint portion joining said one face plate, said connecting plate and said protrusion; said friction stir welding method comprising the steps of: superimposing an end portion of the second member on said recessed portion, while abutting said end portion of said second member against an end portion of said one face plate, thereby providing abutted portions and a joint therebetween; and friction stir welding the abutted portions using a rotary tool having a small-diameter portion mounted on an end of a large-diameter portion, by inserting said small-diameter portion in the joint between said abutted portions and said protrusion; wherein: said protrusion is positioned on the left side of the axial center of said rotary tool as seen when said rotary tool is observed from the direction in which said tool moves along said joint during the friction stir welding; a distance from a tip portion of said inserted small-diameter-portion to a surface of said hollow member opposite from said large-diameter portion is greater on the left side of the axial center of said rotary tool having said protrusion than on the right side thereof, when observed from the direction in which said tool moves during the friction stir welding, said distance from the tip portion of said inserted small-diameter portion to the surface of the first member opposite said large diameter portion on the left side being sufficiently large to avoid flow-out of material of said first member at the left side; and said rotary tool is rotated in a counter-clockwise direction as observed from the large-diameter portion side while being moved along said joint during the friction stir welding. 10. A friction stir welding method according to claim 9, wherein said small-diameter portion of the rotary tool has a screw thread, the screw thread being a right-hand screw thread. 11. A friction stir welding method for welding a first member and a second member, the first member comprising a plate, the plate being provided with a protrusion protruding substantially parallel to said plate from an end portion of said plate and arranged at a displaced position from one surface of said plate, said friction stir welding method comprising the steps of: superimposing an end portion of said second member on said protrusion, and abutting said end portion of said second member against the end portion of said plate, thereby providing abutted portions; and friction stir welding the abutted portions using a rotary tool having a small-diameter portion mounted on an end of a large-diameter portion, by inserting said small-diameter portion into a joint between said abutted portions; wherein during the friction stir welding said rotary tool rotates in a rotational direction and moves along a direction along said joint, whereby pressure of metal mobilized during the friction stir welding is larger on one side of said rotary tool, in said direction that the rotary tool moves along said joint, than on the other side thereof; and a distance from a tip portion of the small-diameter portion of the rotary tool, as inserted into the joint during the friction stir welding, to a surface of the first member, opposite the large-diameter portion, at the one side of the rotary tool having the larger pressure, is greater than a distance from the tip portion of the small-diameter portion of the rotary tool to a surface of the first member, opposite the larger-diameter portion, at the other side of the rotary tool, said distance from the tip portion of the small-diameter portion of the rotary tool, as inserted into the joint during the friction stir welding, to the surface of the first member, opposite the large-diameter portion, at the one side of the rotary tool having the larger pressure is sufficiently large to avoid flow-out of material of said first member at said one side of the rotary tool having the larger pressure. 12. A friction stir welding method according to claim 11, wherein said protrusion is positioned at the side of the welding line, as seen in the direction of movement at said tool when performing said friction stir welding, having the larger pressure.