| 摘要 |
679,080. Making nuts. ILLINOIS TOOLWORKS. Oct. 30, 1950, No. 26433/50. Class 83 (ii). [Also in Group XXV] An undercut counterbore 20 is formed in a nut, to receive and retain a locking washer, by first forming a plain counterbore and then applying axial pressure to upset the lip thereof.
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