Abstract: Provided are a protrusion forming device, a protrusion forming method, and a formed article, with which a height equal to or greater than the plate thickness is possible, the edges are sharp, and cracking can be prevented. This protrusion forming device is characterized by being equipped with a die unit provided with a die hole, and a punch unit having a large punch part with a size such that this part cannot be inserted into the die hole, and a small punch part that protrudes from the large punch part toward the die unit and can be inserted into the die hole, and characterized in that the workpiece is deformed by pressing a portion of the workpiece arranged between the die unit and the punch unit toward the die unit by means of the punch unit, thereby forming a protrusion.

Abstract: A tubular structure includes a tube member provided with annular protrusions, on a side of an insertion opening that is a tube end part or a receiving opening and, on an outer circumference of the tube member, ring members, arranged on an opposite side of the tube end part with respect to the annular protrusions, having two side surfaces that are vertical with respect to an axis of the tube member.

Abstract: Provided is a tubular structure that, even when clearance between a housing and the tubular structure is large, can prevent tube removal and that is capable of absorbing a certain amount of vibration in a lengthwise direction and a manufacturing method therefor. The present invention is a tubular structure comprising a tube member provided with annular protrusions, on a side of an insertion opening that is a tube end part or a receiving opening and, on the outer circumference of the ring member, ring members, arranged on an opposite side of the tube end part with respect to the annular protrusions, having two side surfaces that are vertical with respect to an axis A of the tube member.

Abstract: A form-rolling device for processing a tubular member may include a shaft rotatable around a first axis, a first grooving portion that protrudes from an outer circumference of the shaft; a second grooving portion that is rotatable around a second axis parallel to the first axis; a flange-shaped tube-end positioning member that is attached to a position of the outer circumference of the shaft nearer to a base end than the first grooving portion, and a supporting member that supports an outer circumference of a ring member held on an outer circumference of the tubular member.

Abstract: Provided are a protrusion forming device, a protrusion forming method, and a formed article, with which a height equal to or greater than the plate thickness is possible, the edges are sharp, and cracking can be prevented. This protrusion forming device is characterized by being equipped with a die unit provided with a die hole, and a punch unit having a large punch part with a size such that this part cannot be inserted into the die hole, and a small punch part that protrudes from the large punch part toward the die unit and can be inserted into the die hole, and characterized in that the workpiece is deformed by pressing a portion of the workpiece arranged between the die unit and the punch unit toward the die unit by means of the punch unit, thereby forming a protrusion.

Abstract: A form-rolling device for processing a tubular member may include a shaft rotatable around a first axis, a first grooving portion that protrudes from an outer circumference of the shaft; a second grooving portion that is rotatable around a second axis parallel to the first axis; a flange-shaped tube-end positioning member that is attached to a position of the outer circumference of the shaft nearer to a base end than the first grooving portion, and a supporting member that supports an outer circumference of a ring member held on an outer circumference of the tubular member.

Abstract: Provided is a method of forming a locking ridge for a case of forming the locking ridge on an outer peripheral surface of a joint portion by form rolling, the method realizing a joint portion structure which is superior in pipe detachment prevention performance when pipes with locking ridges are connected by fixing pipe ends with a housing. Using a convex roller arranged inside the workpiece pipe body and a forming circular groove arranged outside the pipe body, the locking ridge is form-rolled such that an upright wall portion thereof is raised at an angle of at least 65° and no greater than 90° with respect to the outer peripheral surface in the pipe axis direction, and that a height of the locking ridge from the outer peripheral surface to the apex of the tip portion is at least a total of curvature radii of faces of the processing means in contact with the pipe body.

Abstract: Provided is a method of forming a locking ridge for a case of forming the locking ridge on an outer peripheral surface of a joint portion by form rolling, the method realizing a joint portion structure which is superior in pipe detachment prevention performance when pipes with locking ridges are connected by fixing pipe ends with a housing. Using a convex roller arranged inside the workpiece pipe body and a forming circular groove arranged outside the pipe body, the locking ridge is form-rolled such that an upright wall portion thereof is raised at an angle of at least 65° and no greater than 90° with respect to the outer peripheral surface in the pipe axis direction, and that a height of the locking ridge from the outer peripheral surface to the apex of the tip portion is at least a total of curvature radii of faces of the processing means in contact with the pipe body.