| 摘要 |
PURPOSE:To produce refill tubes for ball point pens in large quantities at a low cost, by constituting a thin walled main tube part and a fine tube part connecting to the main tube part of metal into one body. CONSTITUTION:Three die surfaces 18 having prescribed curvature are disposed in the central part of a circular cylindrical body 16 in parallel at prescribed intervals. Groove parts 20 are provided in the respective spacing parts, and smoothly finished guiding slopes 24 which incline gently at a prescribed angle from a peak face 22 are formed. While one end part of a stainless steel plank is held gripped and the other end is held pressed to the dies, the blank is inserted into the dies perpendicularly thereto. The stainless steel plank is rotated in this stage and is inserted into the stationary die. A sufficient amt. of oil is injected to the die surfaces to lubricate and cool the pressing faces through the groove parts 20 of the dies. After the pressing for a prescribed length is finished, the plank is pressed for a prescribed time by the above-described operations using the next dies of a smaller diameter. The plank is thus pressed down to a fine tube with the plural dies of gradually smaller diameters. |
