초록 ▼

A tube bulger for producing an enlarged ring-like bulge in the material around an end portion of a metal tube includes upper and lower die sections. When the upper and lower die sections are mated together, a cylindrical hole is formed. The end portion of the tube to be bulged extends into the hole.

A tube bulger for producing an enlarged ring-like bulge in the material around an end portion of a metal tube includes upper and lower die sections. When the upper and lower die sections are mated together, a cylindrical hole is formed. The end portion of the tube to be bulged extends into the hole. A ring-like, outwardly oriented enlargement of the cylindrical hole in the mated die sections forms a bulge cavity into which the bulge moves as it is being formed. An elongated mandrel extends through the opposite end of the cylindrical hole and into the open end of the tube. First and second sealing rings disposed about the mandrel on opposite sides of the bulge cavity prevent leakage of pressurized oil between the die and the mandrel. An oil conducting channel has an opening between the sealing rings. A high pressure oil source forces oil through the channel, out of the opening, thereby applying high pressure to the inner wall of the tube between the first and second sealing rings, causing an initial outward bulging of the tube into the bulge cavity. An enlarged shoulder of the mandrel abuts the open end of the tube, and is moved inward toward the recess, sliding the extreme end portion of the tube toward the bulge cavity. The partially formed bulge engages the wall of the bulge cavity, preventing sliding of the portion of the tube on the opposite side of the bulge cavity. Additional tube material then moves into the bulge cavity while the high pressure continues to be applied. Additional bulging occurs, causing enlargment of the bulge until it fills up the bulge cavity without excessive thinning of tube material in the bulge.

대표청구항 ▼

A method of forming a ring-shaped bulge in a first portion of a piece of metal tube, said tube having a second portion adjacent to the first portion, said method comprising the steps of: (a) inserting the first portion of said piece of tube into a cylindrical hole extending through a die apparatus s

A method of forming a ring-shaped bulge in a first portion of a piece of metal tube, said tube having a second portion adjacent to the first portion, said method comprising the steps of: (a) inserting the first portion of said piece of tube into a cylindrical hole extending through a die apparatus so that the first portion of said tube is in aligned relation with a ring-shaped cavity around and in open communication with the cylindrical hole and defined by an annular enlargement in the wall of the cylindrical hole; (b) applying a predetermined amount of pressure, by means of pressurized fluid inside said tube, to the inside wall of said tube to produce outward bulging of the first portion of said tube and thereby forming an initial portion of the ring-shaped bulge, the initial portion of the ring-shaped bulge extending into said ring-shaped cavity; (c) after the forming of the initial portion of the ring-shaped bulge, applying a longitudinal force to the second portion of said tube, while continuing to apply pressure, by means of the pressurized fluid, to the inside wall of said tube, and thereby causing some of the second portion of said tube to slide into said ring-shaped cavity in order to allow the pressure of the fluid to cause further outward bulging of said initial portion into said ring-shaped cavity without thinning of said tube; and (d) simultaneously with step (c) preventing longitudinal movement of any of the first portion of said tube out of the ring-shaped cavity by causing a portion of the wall of said ring-shaped cavity contacting said initial portion of the ring-shaped bulge to resist longitudinal movement of any of the first portion of said tube out of said ring-shaped cavity.