Abstract: The method of forming a through-hole is capable of preventing formation of burrs, improving machining efficiency and reducing machining cost. The method of forming a through-hole in a circular wall of a cylindrical part of a work piece comprises the steps of: setting the work piece in a die; inserting a punch, which is provided to a rod-shaped metal core and whose length projected from the metal core is shorter than thickness of the circular wall, into the cylindrical part; relatively pressing and moving the punch toward the die so as to drive the punch into an inner face of the circular wall and bore the through-hole; sucking a scrap, which is formed by boring the through-hole, via a discharge hole of the die.

Abstract: The method of forming a through-hole is capable of preventing formation of burrs, improving machining efficiency and reducing machining cost. The method of forming a through-hole in a circular wall of a cylindrical part of a work piece comprises the steps of: setting the work piece to a die; inserting a punch, which is provided to a rod-shaped metal core, into the cylindrical part; and pressing and moving a press pin toward the die together with the punch so as to drive the punch into an inner face of the circular wall and bore the through-hole. The press pin is inserted in the cylindrical part via a guide through-hole, which has been formed in the circular wall of the work piece and which is located on the opposite side of a prescribed position corresponding to the through-hole to be bored, and contacts a surface of the metal core, which is located on the opposite side of the punch.

Abstract: The method of forming a through-hole is capable of preventing formation of burrs, improving machining efficiency and reducing machining cost. The method of forming a through-hole in a circular wall of a cylindrical part of a work piece comprises the steps of: setting the work piece to a die; inserting a punch, which is provided to a rod-shaped metal core, into the cylindrical part; and pressing and moving a press pin toward the die together with the punch so as to drive the punch into an inner face of the circular wall and bore the through-hole. The press pin is inserted in the cylindrical part via a guide through-hole, which has been formed in the circular wall of the work piece and which is located on the opposite side of a prescribed position corresponding to the through-hole to be bored, and contacts a surface of the metal core, which is located on the opposite side of the punch.

Abstract: The method of forming a through-hole is capable of preventing formation of burrs, improving machining efficiency and reducing machining cost. The method of forming a through-hole in a circular wall of a cylindrical part of a work piece comprises the steps of: setting the work piece in a die; inserting a punch, which is provided to a rod-shaped metal core and whose length projected from the metal core is shorter than thickness of the circular wall, into the cylindrical part; relatively pressing and moving the punch toward the die so as to drive the punch into an inner face of the circular wall and bore the through-hole; sucking a scrap, which is formed by boring the through-hole, via a discharge hole of the die.