WORKING A NATURAL OR SYNTHETIC HARD STONE SUCH AS A GEMSTONE

摘要

For blocking or polishing a natural or synthetic stone having a Mohs hardness greater than 5, a blocking head has a body, a mounting member 9 which can move vertically with respect to the body, and a rotary spindle driven by a motor 12. The mounting member 9 is carried by a leaf spring 22 whose position is altered by a parallel linkage 23, 25, 26 whose arm 26 is driven by a motor. In this way, the spring 22 can for soft landing apply an upwards bias opposing the gravitational force of the mass of the mounting member 9. When the stone 3 is in contact with the scaife, the deflection of the spring 22 measures the force on the stone 3, and this deflection is detected by an LVDT 15. Subsequently, the spring 22 can apply a downwards bias to augment the working force. A microprocessor is responsive to the output of the LVDT 15 and controls the motor so that the force applied to the stone 3 complies with a predetermined programme.