| 摘要 |
Method of producing a multi-layer filter from a multiplicity of flat filter elements such as wire gauze, perforated sheet or the like where the individual filter elements have different degrees of fineness, including arranging the multiplicity of filter elements in an assembly having smooth gradations of fineness with the finest material at one end and the coarsest material at the other end of the assembly; welding or soldering the assembly of filter elements together in an area including the periphery of the final multi-layer filter to be made; aligning the welded or soldered assembly in a conventional punching means having a punching tool with the end of the assembly containing the finest filter element directed toward the punching tool and with the punching tool aligned with the welded or soldered area, and activating the punching means whereby to cut out a filter from said assembly within the welded or soldered area and at the same time forcing the finer filter layers at least partially around the next adjacent more coarse filter layers and stretching the filter layers in proportion to their fineness. |
