| 摘要 |
<p>A method of forming blind holes in a sheet material is provided. The method includes punching the sheet material to define a hollow projection through the material and shearing a layer of material from the sheet material to form a sealed end over an opening of the hollow projection to form the blind hole. Further processing of the sheet material may be required depending on the desired diameter of the blind hole. Such further processing includes enlarging the hollow projection to a desired diameter of the blind hole and shearing the layer of material with several tapered pins with progressively decreasing diameters. As the scaled end formed is likely to have an uneven surface, the sealed end may be flattened to render a more refined appearance.</p> |
