| 摘要 |
PROBLEM TO BE SOLVED: To contrive the reduction of the driving torque and also to prevent the fall-off of a fiber from the cutting end part by reducing the contact between liners and a recording medium in such a manner that the liners having nearly octagonal outside shapes are welded so as tightly on the whole circumference also for the outer peripheral corner parts. SOLUTION: As to the fixing operation of the liners 5, 6 respectively to the inner surfaces of upper/lower shells 1, 2 confronted with the recording medium 4 which is rotatably housed in a case C consisting of the upper shell 1 and lower shell 2, the arrangement is made in such a manner that the shape of a welding horn for welding the liners 5, 6 having the nearly octagonal outside shapes to the inner surfaces of the shells 1, 2 is formed to the octagonal shape equal to the outside shapes of the liners 5, 6 and the outer peripheral part is welded over the whole circumference along the shapes of the liners 5, 6.
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