| 摘要 |
PURPOSE:To obtain the titled plate capable of providing a high-quality glass fiber, etc., having uniform thickness, excellent dimensional accuracy and which is hardly cracked by machining the rear surface of a bushing plate on which circular protrusions are formed by using a specified die and boring a nozzle hole through the circular protrusion. CONSTITUTION:A busing plate material 1' (e.g., Pt-Rh alloy) is inserted between the upper die 12 having plural protruded tracks 11 on the lower surface and the lower die 14 having staggered circular tapered chip holes 13 on the upper surface while opposing to the protruded track 11 and pressed to form many circular protrusions 5 on the plate 1'. Then the whole surface of the protrusion 15 on the rear surface side is machined to form a flat surface 1a. The tapered nozzle hole 17 is concentrically bored through many circular protrusions from the flat surface 1a side by using a punch 23 and a reamer 24 to form a nozzle 18. |
