Patent ID: 7083352

Claim:
A ballpoint pen comprising: a tip body made of metal having a front edge part and a plurality of inward protrusions, the front edge part being inwardly bent at a front edge of the tip body, and the inward protrusions being formed by pressure deformation and located on the inner side wall of the tip body and at a rearward portion of the front edge part; a ball rotatably embraced between the front edge part and the inward protrusions; and a rod part urging the ball forwardly and bringing the ball into close contact with the inner surface of the front edge part, wherein ink outflow gaps extended outwardly in a radial direction from the center of the tip body are formed each between the adjacent inward protrusions, the rod part is inserted into the space defined by the ink outflow gaps, the diameter of a virtual inscribed circle of the central part of the ink outflow gaps is larger than the outside diameter of the rod part, and a minimum dimension of each the ink outflow gap is smaller than the outside diameter of the rod part, wherein a radius of curvature at the apex of the inward protrusions is larger than the radius of the ball.