| 摘要 |
PROBLEM TO BE SOLVED: To form a uniform and stabilized seat surface, eliminate the unevenness in the seating of a ball and also eliminate the fluctuation of ink flow rate in the writing direction by using a conical face formed as a ball receiving seat by setting the wall of a fine metal tube along the conical section and a fine diameter section of a core pin with a step. SOLUTION: In the case of adopting a plastic processing method in a foregoing process, surging is generated on an upper end opening edge 12, and the surged sections are removed by a method of press cutting the upper end by the corners of a cutting or a rotating roll and a core pin or the like to shape the upper end opening edge 12. As a following process, ink channels 14 are formed by punching and forming several vertical channels or a ball seat 7 and a ball 15 is fitted thereon, and then the upper end opening edge 12 is caulked inwardly and the ball 15 is wrapped to form a ball point pen tip. The caulking is completed by caulking to the degree of forming a clearance for flowing ink between the ball 15 and a caulking section 13 until the caulking section is made to adhere to the ball 15 and then the ball 15 is hit and sunk to form a proper clearance or the like. |
