| 摘要 |
1,104,909. Models for copying. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 11 March, 1966 [13 March, 1965], No. 10818/66. Headings B3B and B3K. A method of making a die for use in compressing or moulding a part comprises drawing or engraving a series of large-scale cross-sections of a model 1 of the part on flat non-deformable plates 4, each plate containing reference lines or apertures 6, 7, 8, the cross-sections then being transferred to a block of readily-machinable non-deformable material, shaping the block to the finished shape, and finally producing the die from the block with an appropriate reducing means. The model 1 of a hearing aid is made from balsawood, clay, &c. From the model must be made inner and outer dies for moulding upper and lower halves 2, 3. The plates 4 of methyl methacrylate are engraved to a depth of 0À6 mm. with the large scale cross-sectional outlines by a high speed cutter having a tip of 60 degrees. The crosssections are spaced by the thickness of the plates, or plates and spacers, and separate plates are made for inner and outer circumferences of the sections. The engraved plates are stacked on rods 10 and are used for copy-milling blocks of synthetic material with a series of steps. These blocks are then smoothed out by hand to produce shapes such as shown in Fig. 9. The blocks are used as models for copy-milling, down to the correct size, the actual dies in tool steel or bronze. In a modification, the cross-sections are taken along a circular arc. In a further modification, the smoothed large-scale blocks are used to form fine-grained cement coats so that no reversal of copying is required in producing the actual dies. |
