| 摘要 |
The invention relates to an apparatus for drawing a monocrystal from a crucible by means of a coilable pulling element having the end that is located above the crucible secured a crystal-nucleus holder. The pulling element, which is preferably a steel cable, is connected to a lifting drive which is arranged on a platform which is rotatable about the pulling element. The lifting drive comprises a driven horizontal shaft with a longitudinally displaceable coiling drum thereon, onto which drum the pulling element can be tangentially coiled. The vertical speeds of the crystal-nucleus holder can be adjusted to speeds which differ greatly from each other by providing the lifting drive with a drive motor for rapid operation and a drive motor for flow operation, which motors act on the coiling drum by way of shafts which can be disconnected from each other by means of a clutch but which are disposed coaxially. In this arrangement, the drive motor for rapid operation is connected to the non-disengageable shaft and the drive motor for slow operation is connected to the disengageable shaft. |
