| 摘要 |
PURPOSE:To expand a reproducing band width by heating a thermoplastic resin film which preserves a circumferential part, vacuum-absorbing an oscillating part forming part to the mold main body, stretching the circumferential part and next, absorbing the edge part to the mold main body. CONSTITUTION:On an air heater 11 provided with a heater 10, the thermoplastic resin film 12 is arranged. A forming mold 14, which has an oscillating part forming part 16 at the center, a cross sectional wave-shaped edge part forming part 15 at the outer circumferential part and further, a circumferential part stretching part 21 at the outside, is preserved at a mold holder 13 on the film 12. The mold 14 is descended, only a vacuum absorbing hole 19 of the forming part 16 is made vacuum, the film 12 is absorbed and next, the peripheral part of the film 12 is vacuum-absorbed and stretched through a groove 20. Next, the peripheral part of the film 12 is absorbed to a forming part 15 part of the mold 14, cooled in such a condition, removed from the mold 14 and the unnecessary part of the circumference is cut. |
