| 摘要 |
1,045,729. Grinding. GILLETTE INDUSTRIES Ltd. Sept. 27, 1965 [Oct. 16, 1964], No. 42352/64. Heading B3D. An end of a small bore metal tube is ground to a desired configuration while the bore of the tube is filled with a core of ice, whereby the formation of burrs is prevented or reduced to within acceptable limits. In the manufacture of surgical needles, water under pressure is forced into a length of stainless steel tubing to fill the bore completely, the water being retained by capillary action. The water may be distilled water or may contain additives such as those used in the coolant used in subsequent grinding. The tube is then immersed in solid carbon dioxide at a temperature of -75‹ C. for a minute or longer; liquid air or nitrogen may be used. One end of the tube is then given the desired point configuration by a grinding wheel. Coolant is supplied to the working zone either at room temperature or refrigerated, e.g. at - 5‹ C. The pointed tube is then subjected to further grinding to form a bevelled facet on one or both sides of the point; the bore of the tube may be filled with ice during this bevel grinding. |
