Driving mechanism for crystal-pulling rod - using two magnetic clutches for fast and slow speeds

摘要

The device consists of a crystal-pulling rod and two separate motor drives. The slow speed axial motion of the rod is obtd. using one motor to rotate a threaded spindle via a worm and worm-wheel, the pulling rod being located in the threaded bush which is prevented from rotating by an electromagnetic coupling (I). The pulling rod is also rotated using the second motor and a pair of gears. When rapid axial movement of the pulling rod is required, coupling (I) is switched off and a second electromagnetic coupling used to link the rod to the gear-drive on the second motor, i.e. the two coupling are used alternately to obtain slow or fast rod motion. Only two driving motors are required and no inter. gear trains is needed.