SPHERICAL ROUGH GRINDER FOR LENS

PURPOSE:To make the required revolution of a lens possible to be set without measuring the time required for on revolution in the case where rotational frequency is changed according to a lens material, by connecting a lens revolving speed measuring part installed in a rotational part to a controller. CONSTITUTION:Rotating a motor 7, when a lens holder 4 and a grindstone 11 are rotated, a notched disc 20 rotates whereby a photoelectric sensor 21 detects each notch 22, transmitting a signal to a controller 17 with measures the rotation frequency of a lens. Simultaneously, with a command out of the controller 17, a pulse motor 15 is driven, and a workhead 5 advanced forward toward the grind stone 11, pressing the lens 3 to the grindstone 11, and when the motor 15 is driven will the specified pulse number is counted, the workhead 5 is fed up to the specified position and tops. Next, the controller 17 counts signals out of the sensor 21, and when it counts signals equivalent to a portion of one rotation of the lens 3, the controller 17 reverses the motor 15, making the workhead 5 retract, so that the lens 3 comes off the grindstone 11.