| 摘要 |
<p>PURPOSE:To enable the plastic disk excellent in the uniformity of thickness distribution in radial direction and shape stability by causing the thickness in the axial direction of a molding cavity to become thick continuously, as the part of said thickness goes away from a gate. CONSTITUTION:A molding cavity is sectionally formed by split molds 1, 2. The thickness in the axial direction of a stamper 4 is tapered so as to part from the imaginary central surface 6 of a molding cavity such that the thickness of the stamper becomes thin, as the part of said thickness goes away from a gate 5. The dimension of the sectionally formed molding cavity 3' is thin at a central portion and thick at a peripheral portion. The difference d(D1-D2) between the thickness D2 (minimum value) in the axial direction of the molding cavity adjacent to a central gate and the thickness D1 (maximum value) in the axial direction adjacent to the peripheral portion may be preferably d=10-50mum. In short, the thickness distribution in the radial direction of a final product is selected to become uniform at the given condition of injection molding.</p> |
