| 摘要 |
<p>PURPOSE:To correctly regulate and to easily change a protruded quantity by pressurizing a forming tool rotating around a shaft center from the inside of a fixed drum and protruding and forming a protruded part in the manufacturing process of a fixed drum at a helical scanning system VTR. CONSTITUTION:A forming tool 7 is pressed from the inside of a fixed drum 1 and a protruded part is formed without damaging a tape traveling surface 2. The forming tool 7 is rotated, protruded parts 4 and 5 are formed without giving the influence to the circularity of the tape traveling surface 2, and the surface coarseness of formed protruded parts 4 and 5 is made to <=3mum. The swell does not rise at the upper edge surface of a fixed drum 1 and there is not a danger than an obstacle occurs at the passing clearance of a magnetic head. By the regulation of the rotation direction of the forming tool 7, the protruded parts 4 and 5 can be made into the smooth shape toward a tape winding part, even when a magnetic tape 3 passes through the protruded parts 4 and 5, it can be contacted and detached to the tape traveling surface 2, a jitter can be further eliminated and the tap noise of the magnetic tape due to the magnetic head can be eliminated.</p> |
