Patent ID: 7464468

Claim:
A method for manufacturing a ring which is made of a rigid material and inlaid with a precious metal, the method comprising the steps of: fabricating an annular blank by compressing a powdered mixture including 80 to 85 weight percent of tungsten carbide in a mold by means of a hydraulic press; sintering the annular blank in an electric furnace of a vacuum state for 40 to 50 hours under a temperature of 1750 to 1850° C.; primarily polishing upper, lower, inner peripheral and outer peripheral surfaces of the sintered annular blank by a wheel of which an outer peripheral surface is attached with diamond powder, and forming curved surfaces in both lateral sides of the inner peripheral surface of the annular blank by grinding the both lateral sides of the inner peripheral surface of the annular blank using the wheel; smoothing surfaces of the annular blank by rotating and vibrating a container after inputting the primarily polished annular blank into the container together with abrasives; secondarily polishing the inner and outer peripheral surfaces of the annular blank by a buffing tool of which an outer peripheral surface is attached with diamond powder; fixing the secondarily polished annular blank in a rotary jig, and performing a grooving process with respect to a center portion of the outer peripheral surface of the annular blank for 30 to 35 hours by the wheel, thereby forming an annular groove having a predetermined depth at the outer peripheral surface of the annular blank; slantingly cutting both sidewalls of the annular groove in a downward direction by means of a diamond bite, thereby forming inwardly inclined slots having a gradient identical to that of the inclined sidewalls at both lower edge portions of the annular groove, in which the lower edge portions are formed between a bottom wall and both inclined sidewalls defining the annular groove; preparing a strip type precious metal having a predetermined length and a predetermined thickness forming a predetermined volume, which is 1.1 to 1.5 times larger than that of the annular groove, fitting the annular blank around a tapered rod, manually inserting one end of the strip type precious metal into the annular groove, and striking the strip type precious metal against the bottom surface of the annular groove lengthwise along the strip type precious metal from the one end of the strip type precious metal to the other end with an iron hammer; and removing a step difference between an upper surface of the precious metal and the outer peripheral surface of the annular blank by finely cutting the outer peripheral surface of the annular blank together with the upper surface of the precious metal using a diamond bite.