| 摘要 |
PURPOSE:To prevent a thread once held from derailing again due to thread tension, by forming concave portions at the outside of surface portions in order to let the surface portions of a thread holding groove swell out at more than one portion of the thread holding groove, when manufacturing bobbins for thread reels. CONSTITUTION:A bobbin 1 has a groove 2 to guide and hold a thread, and has plural concave portions along the both sides of the groove 2. The groove 2 consists of thread guide groove 2a and thread hold groove 2b. A swollen portion 4 is provided on the surface portion of the thread hold groove 2b. The swollen portion 4 is formed by the concave portion 3 outside the groove 2. At first the groove 2 is cut to make the swollen portion 4 touch with the groove 2. Next, concave portions 3 are made by such as a punch near the groove 2 with an interval corresponding to the width of the swollen portion 4. Then the surface portion of the groove side is pushed out to the thread holding groove 2b side, and the surface portion is swollen to the thread holding groove 2b side leaning to the groove side, and comes in contact with the side wall of the opposite side of the thread holding groove. |
