| 摘要 |
<p>PURPOSE:To prevent the loss of driving power without increasing friction force even if the front end of a head wears by notching the rear surface side of a work to form a recessed part, cutting a front surface side and forming a projecting part on the front surface side integrally with a middle drum. CONSTITUTION:The rear surface side of the work 30 is notched to form a recessed part 30b and the front surface side is cut by a cutting tool 40. Cutting resistance is generated according to the cutting direction and cutting force at the time of this cutting and the force perpendicular to the front surface 30a of the work 30 acts thereon. The part near the center on the recessed part 30b side is then strongly pressed and deflected. This recessed part 30b restores the original shape after the working, by which the projecting part 33 of nearly the same height as the projecting height of a magnetic head 31 is integrally formed on the front surface side. Since the projecting part 33 is formed integrally on the middle drum 14 in such a manner, the increase in the friction force by contact of the surface of the middle drum 14 with a magnetic tape is prevented by the projecting part 33 even if the top end of the head 31 is slightly worn after relatively long-term use according to the rotary drum device. The loss of the friction force at the time of allowing the tape to travel is thus prevented.</p> |
